[Federal Register Volume 73, Number 24 (Tuesday, February 5, 2008)]
[Proposed Rules]
[Pages 6660-6684]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 08-493]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R6-ES-2008-0013; 1111 FY07 MO-B2]


Endangered and Threatened Wildlife and Plants; 12-Month Finding 
on a Petition To List the Gunnison's Prairie Dog as Threatened or 
Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of a 12-month petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce our 
12-month finding on a petition to list the Gunnison's prairie dog 
(Cynomys gunnisoni) as an endangered or threatened species under the 
Endangered Species Act of 1973, as amended (Act). After a thorough 
review of all available scientific and commercial information, we find 
that the species is not threatened or endangered throughout all of its 
range, but that the portion of the current range of the species located 
in central and south-central Colorado and north-central New Mexico (the 
northeastern portion of the range) represents a significant portion of 
the range where the Gunnison's prairie dog is warranted for listing 
under the Act. Currently, listing is precluded by higher priority 
actions to amend the Lists of Endangered and Threatened Wildlife and 
Plants. We have assigned a listing priority number (LPN) of 2 to this 
species, because threats have a high magnitude, and are imminent. We 
will develop a proposed rule to list the Gunnison's prairie dog in the 
northeastern (montane) portion of its range as our priorities allow.

DATES: This finding was made on February 5, 2008.

ADDRESSES: This finding is available on the Internet at http://www.regulations.gov and http://www.fws.gov/mountain-prairie/species/mammals/gunnisonprairiedog. Supporting documentation we used to prepare 
this finding is available for public inspection, by appointment, during 
normal business hours at the U.S. Fish and Wildlife Service, Western 
Colorado Field Office, 764 Horizon Drive, Building B, Grand Junction, 
CO 81506-3946; telephone (970) 243-2778; facsimile (970) 245-6933. 
Please submit any new information, materials, comments, or questions 
concerning this finding to the above address.

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FOR FURTHER INFORMATION CONTACT: Al Pfister, Field Supervisor, U.S. 
Fish and Wildlife Service, Western Colorado Field Office (see 
ADDRESSES). If you use a telecommunications device for the deaf (TDD), 
call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Background

    Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.), requires 
that, for any petition containing substantial scientific and commercial 
information that listing may be warranted, we make a finding within 12 
months of the date of receipt of the petition on whether the petitioned 
action is--(a) not warranted, (b) warranted, or (c) warranted, but that 
immediate proposal of a regulation implementing the petitioned action 
is precluded by other pending proposals to determine whether species 
are threatened or endangered, and whether expeditious progress is being 
made to add or remove qualified species from the Lists of Endangered 
and Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act 
requires that we treat a petition for which the requested action is 
found to be warranted but precluded as though resubmitted on the date 
of such finding; that is, requiring a subsequent finding to be made 
within 12 months. We must publish these 12-month findings in the 
Federal Register.

Previous Federal Actions

    On February 23, 2004, we received a petition from Forest Guardians 
and 73 other organizations and individuals requesting that the 
Gunnison's prairie dog (found in Arizona, Colorado, New Mexico, and 
Utah) be listed as threatened or endangered.
    On July 29, 2004, we received a 60-day notice of intent to sue for 
failure to complete a finding. On December 7, 2004, an amended 
complaint for failure to complete a finding for this and other species 
was filed. We reached a settlement agreement with the plaintiffs, and 
on February 7, 2006, we published a 90-day finding in the Federal 
Register (71 FR 6241) determining that the petition did not present 
substantial scientific information indicating that listing the 
Gunnison's prairie dog species may be warranted.
    On August 17, 2006, Forest Guardians and eight other organizations 
and individuals provided written notice of their intent to sue 
regarding the determination in the 90-day finding. On December 13, 
2006, the plaintiffs filed a complaint challenging the finding. On June 
29, 2007, we reached a settlement agreement with the plaintiffs for 
submittal to the Federal Register of a 12-month finding by February 1, 
2008. The court adopted the terms and conditions of the agreement on 
July 2, 2007.
    On August 28, 2007, we published a notice initiating the 12-month 
finding and opening a 60-day public comment period on the Gunnison's 
prairie dog (72 FR 49245).

Species Information

    A description of the Gunnison's prairie dog is included in the 90-
day petition finding (71 FR 6241; February 7, 2006) and in a concise 
review of the published information by Underwood (2007, pp. 6-13). In 
addition, we used data in the Western Association of Fish and Wildlife 
Agencies' (WAFWA) Gunnison's Prairie Dog Conservation Assessment 
(Seglund et al. 2005) to complete much of our analysis in this finding.
    The Gunnison's prairie dog has sometimes been divided into two 
subspecies: Cynomys gunnisoni gunnisoni and C. g. zuniensis (Hollister 
1916, p. 29). We currently regard the Gunnison's prairie dog as a 
single species because the most recent published analyses (Goodwin 
1995, pp. 100, 101, 110; Pizzimenti 1975, pp. 11, 15, 63) do not 
support subspecies designation. Unpublished research (Hafner 2004, p. 
6; Hafner et al. 2005, p. 2) indicates that the distribution of 
mitochondrial DNA (deoxyribonucleic acid) haplotype lineages supports 
past geographic isolation, followed by limited mixing in regions 
coincident with the recognized borders of the two purported subspecies. 
Although this analysis will likely be substantiated through additional 
research, it is still preliminary and needs to be verified before we 
can use it as evidence for subspecies designation. For the same 
reasons, although Gunnison's prairie dogs in montane habitat may be 
``markedly separate'' from those in prairie habitat, we are not 
proposing listing the montane prairie dogs as a distinct population 
segment (DPS) under our Policy Regarding the Recognition of Distinct 
Vertebrate Population Segments Under the Endangered Species Act (61 FR 
4722; February 7, 1996). We anticipate that future funding may become 
available for genetic, taxonomic, and range research to determine 
whether subspecies or DPS status is valid.
    Gunnison's prairie dogs are a colonial species, historically 
occurring in large colonies over large areas. Colonial behavior offers 
an effective defense mechanism by aiding in the detection of predators, 
but it also can play an important role in the transmission of disease 
(Antolin et al. 2002, p. 19; Biggins and Kosoy 2001, p. 911). Complexes 
of Gunnison's prairie dog colonies (metapopulations) expand or contract 
over time depending upon various natural factors (such as reproduction, 
food availability, and disease) and human-caused factors (such as 
chemical control and shooting). To substantially augment depleted 
populations or replace populations without human intervention, a 
metapopulation structure is required across the landscape so that 
migration between colonies is possible (Gilpin and Soule 1986, p. 24; 
Clark et al. 1982, pp. 574-575; Lomolino and Smith 2001, p. 938).

Habitat

    Gunnison's prairie dog habitat includes level to gently sloping 
grasslands and semi-desert and montane shrublands, at elevations from 
6,000 to 12,000 feet (1,830 to 3,660 meters) (Bailey 1932, p. 125; 
Findley et al. 1975, p. 133; Fitzgerald et al. 1994, p. 183; Pizzimenti 
and Hoffman 1973, p. 1; Wagner and Drickamer 2002, p. 4). Grasses are 
the most important food item, with forbs, sedges, and shrubs also 
occasionally used (Pizzimenti and Hoffman 1973, p. 3; Shalaway and 
Slobodchikoff 1988, p. 840).
    Gunnison's prairie dog range can be considered to occur in two 
separate range portions--higher elevations in the northeast part of the 
range and lower elevations elsewhere (Bailey 1932, pp. 125-127; 
Pizzimenti and Hoffman 1973, pp. 1-2; Hall 1981, p. 7; Knowles 2002, p. 
4). We refer to these areas as montane and prairie, respectively, 
throughout the document to differentiate them; however, we recognize 
that these terms are an oversimplification of the actual habitats 
present, and describe them in more detail below.
    In Figure 1, we provide a map illustrating the division of the 
general range of the species into the northeastern (montane) and 
southwestern (prairie) portions. The outer boundary in Figure 1 is 
referenced from maps depicting the species' gross range (Hollister 
1916, p. 24; Pizzimenti and Hoffman 1973, p. 2; Pizzimenti 1975, p. 4; 
Hall 1981, p. 415; Knowles 2002, p. 6), and from maps of the species' 
range in Arizona (Hoffmeister 1986, p. 194), Colorado (Armstrong 1972, 
p. 139; Fitzgerald et al. 1994, p. 185), New Mexico (Findley et al. 
1975, p. 133), and Utah (Durrant 1952, p. 106). An approximate boundary 
dividing the montane and prairie range portions was established from 
several maps that recognize discrete range portions for each of the two 
purported subspecies,

[[Page 6662]]

Cynomys gunnisoni gunnisoni and C. g. zuniensis (Hollister 1916, p. 24; 
Armstrong 1972, p. 139; Pizzimenti and Hoffman 1973, p. 2; Pizzimenti 
1975, p. 4; Hall 1981). Maps that depict the geographic variation in 
Gunnison's prairie dog mitochondrial DNA in southern Colorado and 
northern New Mexico (Hafner 2004, p. 6; Hafner et al. 2005, p. 2) were 
used to improve the resolution of the montane and prairie boundary in 
this region, as these maps provide a boundary based on genetic 
differences between Gunnison's prairie dogs in the two range portions. 
Lastly, we used topographic maps to adjust the boundary on a finer 
scale along the mountain ranges and ridges of southern Colorado and 
northern New Mexico, because geography partly separates the Gunnison's 
prairie dog populations and allows limited overlap between the two 
range portions (Knowles 2002, p. 3; Hafner et al. 2005, p. 1).
    In summary, the maps we used to delineate the montane and prairie 
range portions vary in their age, projection, scale, and accuracy, and 
depict boundaries based on geography, morphological traits of 
Gunnison's prairie dog populations, and genetic characteristics from 
Hafner's work (Hafner 2004, p. 6; Hafner et al. 2005, p. 2). They 
contribute to the best available information used to establish the 
montane and prairie portions of the species' range for further 
analysis.
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[GRAPHIC] [TIFF OMITTED] TP05FE08.000

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Montane Habitat

    The northeastern range (central and south-central Colorado, and 
north-central New Mexico) consists primarily of higher elevation, 
cooler and more mesic plateaus, benches, and intermountain valleys. We 
call this portion ``montane'' for ease of reference, and it comprises 
approximately 40 percent of the total potential habitat within the 
current range. Gunnison's prairie dogs occupy grass-shrub areas in low 
valleys and mountain meadows within this habitat (Seglund et al. 2005, 
p. 12). The Gunnison's prairie dogs in this portion of the range are 
limited by pronounced physiographic barriers (Pizzimenti and Hoffman 
1973, p. 1), including the Uncompahgre Plateau and San Juan mountains 
in Colorado and Utah, and the Sangre de Cristo, San Juan, and Jemez 
mountain ranges in New Mexico.

Prairie Habitat

    The southwestern range (southeastern Utah, southwestern Colorado, 
northwestern New Mexico, and northeastern Arizona) consists primarily 
of lower elevation, warmer and more xeric plains and plateaus (Bailey 
1932, pp. 125-127; Pizzimenti and Hoffman 1973, pp. 1-2; Hall 1981, p. 
7; Knowles 2002, p. 4). We call this portion ``prairie'' for ease of 
reference, and it comprises approximately 60 percent of total potential 
habitat within the current range. Gunnison's prairie dogs occupy 
shortgrass and mid-grass prairies within this habitat (Seglund et al. 
2005, p. 12).

Distribution, Abundance, and Trends

    The current distribution of the species includes northeastern 
Arizona; central, south-central, and southwestern Colorado; north-
central and northwestern New Mexico; and extreme southeastern Utah 
(Bailey 1932, pp. 125-127; Pizzimenti and Hoffman 1973, pp. 1-2; Hall 
1981, p. 7; Knowles 2002, p. 4) (see Figure 1 above). Limited overlap 
occurs in the ranges of Gunnison's prairie dogs and black-tailed 
prairie dogs (Cynomys ludovicianus) in New Mexico (Goodwin 1995, p. 
101; Sager 1996, p. 1), and Gunnison's prairie dogs and white-tailed 
prairie dogs (Cynomys leucurus) in Colorado (Knowles 2002, p. 5), but 
we have no evidence that interbreeding is occurring. Currently, 27 
percent of potential Gunnison's prairie dog habitat occurs in Arizona, 
25 percent in Colorado, 45 percent in New Mexico, and 3 percent in Utah 
(Seglund et al. 2005, p. 83). We used the data in Seglund et al. (2005, 
pp. 82, 85-87) to calculate that approximately 22 percent of the 
potential habitat occurs on private lands, 12 percent on State lands, 
17 percent on Federal lands, and 49 percent on Tribal lands/Bureau of 
Indian Affairs (BIA). The Tribal lands habitat occurs mostly in Arizona 
and New Mexico; a large amount of potential habitat is on Navajo lands 
(Cole, p. 1).
    Most estimates of prairie dog populations in the available 
literature are expressed in terms of area (acres (ac) or hectares (ha)) 
of occupied habitat rather than in numbers of individuals, most likely 
because counting individuals is feasible only for small areas (Biggins 
et al. 2006, p. 94). Also, the number of animals present in a locality 
has been observed to vary with habitat, season, colony age, 
precipitation, forage, predation, disease, chemical control, shooting, 
and other factors (Knowles 2002, pp. 7-8); density of individuals 
typically ranges from 2 to 23 per ac (5 to 57 per ha) (Fitzgerald et 
al. 1994, p. 184). Most prairie dog surveys do not result in a density 
estimate because of the associated effort and cost. Estimates of 
Gunnison's prairie dog occupied habitat provide one of the best 
available and most reasonable means of evaluating the status of the 
species across its range.
    Obtaining estimates of occupied area is itself time-consuming and 
costly. Ground or aerial mapping of colonies over a predicted habitat 
range of 23 million ac (9.5 million ha) in 4 States would be required 
to determine a rangewide estimate of the area occupied by the 
Gunnison's prairie dog (Seglund et al. 2005, pp. 17-19). Recent 
attempts at less expensive aerial surveys (for example, air photo 
interpretation) have been limited in their effectiveness when applied 
to Gunnison's prairie dogs (Johnson et al. 2006, p. 3; Seglund et al. 
2005, pp. 23-24). Whether surveying is performed from the air or on the 
ground, it is often difficult to accurately and consistently discern 
colony boundaries (thus introducing error in the area measurements). 
Older studies did not benefit from technologies such as global 
positioning systems and geographic information systems (GIS) in mapping 
colonies. Accuracy suffers when studies are performed over the longer 
time intervals necessary to visit large range portions, because colony 
area, location, and persistence on the landscape often change 
relatively quickly (Wagner et al. 2006, p. 335).
    In summary, we recognize that different methodologies were used at 
different times and in different locales to derive the various 
historical occupied area estimates we obtained for review. These 
estimates contribute to the best available information, and we consider 
them comparable for determining long-term population trends, while 
acknowledging potential error margins on the scale of an order of 
magnitude.
    Since our 90-day finding in 2006, all States within the range of 
the species have applied occupancy modeling methodology to investigate 
the habitat occupied by Gunnison's prairie dogs. This is a newer 
technique that yields estimates of the percentage of random plots 
occupied across the habitat range under consideration (MacKenzie et al. 
2002, pp. 2248-2249; MacKenzie et al. 2003, pp. 2200-2201). These 
estimates are statistically based and, therefore, are considered more 
objective (Andelt et al. 2006, pp. 1-2; Colorado Division of Wildlife 
(CDOW) 2007, p. 19; WAFWA 2007, p. 4).
    A drawback is that estimates of percent occupancy by Gunnison's 
prairie dogs are not directly comparable to estimates of occupied acres 
(including most historic estimates), because when a random plot is 
visited, only detection or non-detection (not acres occupied) is 
recorded by the observers. If mapping is not performed during a site 
visit, no information about colony or complex size or location is 
obtained.
    The positive aspects of this method are statistical rigor, 
precision estimates, large-scale application in a single season, and 
trend analysis if performed over subsequent years. In addition, the 
results of individual surveys can be interpreted separately to assess 
prairie dog occupancy and document trends within in specific areas of 
concern. Although only a single year (2007) of occupancy modeling 
results are available (with the exception of Colorado data from 2005 
and 2007), we used these estimates, along with estimates of occupied 
areas, to assess the status and trends of the Gunnison's prairie dog in 
each of the four States.

Historical Estimates of Abundance

    Historical estimates of Gunnison's prairie dog occupied habitat in 
Arizona and New Mexico are available from Federal records of early 
poisoning efforts, such as by the Bureau of Land Management (BLM) and 
the U.S. Forest Service (USFS). In 1916, approximately 6.6 million ac 
(2.7 million ha) of Gunnison's prairie dog occupied habitat occurred in 
Arizona, and 11 million ac (4.4 million ha) occurred in New Mexico 
(Oakes 2000, pp. 169-171). In our 90-day finding in 2006 (71 FR 6241, 
February 7, 2006), we calculated historical estimates (circa 1916) for 
Colorado (6 million ac (2.4 million ha)) and Utah (700,000 ac (284,000 
ha)) from prairie dog information in various

[[Page 6665]]

publications and reports, because data were not available for these 
States. By summation, based on the best available information, our 
rangewide estimate for historic (circa 1916) Gunnison's prairie dog 
occupied habitat was approximately 24 million ac (9.7 million ha).
    In 1961, an estimated 445,000 ac (180,000 ha) of habitat was 
occupied by Gunnison's prairie dog in Arizona; 116,000 ac (47,000 ha) 
in Colorado; 355,000 ac (144,000 ha) in New Mexico; and 100,000 ac 
(41,000 ha) in Utah (Bureau of Sport Fisheries and Wildlife 1961, pp. 
1, 5). By summation, the rangewide estimate for Gunnison's prairie dog 
occupied habitat in 1961 was approximately 1 million ac (405,000 ha). 
These data suggest that, from 1916 to 1961, Gunnison's prairie dog 
populations decreased by approximately 93 percent in Arizona, 98 
percent in Colorado, 97 percent in New Mexico, and 86 percent in Utah, 
or by approximately 95 percent rangewide. However, historic declines 
may not support a conclusive inference that current populations 
continue to decline.
    In summary, empirical data on acres occupied indicate that, between 
1916 and 1961, habitat occupied by the Gunnison's prairie dog 
throughout its range declined from approximately 24,000,000 ac 
(9,700,000 ha) to approximately 1,016,000 ac (406,400 ha).

Statewide Estimates of Abundance

    As indicated above, estimates of percent occupancy arrived at 
through recent occupancy modeling (presence or absence at a random 
plot) do not equate to acres occupied. The method currently used by 
States to assess the Gunnison's prairie dog's status, in conjunction 
with both historic and recent mapping efforts, provides empirical data 
on percent occupancy of potential habitat. This data is useful as a 
gross-scale comparison to historical estimates of acres occupied. Both 
types of data are valid and represent the best available science.
    Full occupancy of surveyed habitat would not directly equate to 100 
percent of available habitat, but it would provide a gross 
approximation of occupancy at a larger geographic scale. For the 
purposes of interpreting the percent occupancy numbers in this 
document, current State survey efforts utilize a scale from 1 to 100, 
indicating the percentage of occupied cells surveyed. Because we do not 
have historical data on percent of habitat occupied or on occupancy 
rates, we use the current percentage of occupied habitat to compare 
between habitats that currently appear to have a functional 
metapopulation structure (prairie) and that do not (montane). For 
example, the following paragraphs illustrate that Gunnison's prairie 
dog occupancy in plots sampled in montane habitat is estimated to be 
approximately 3.6 percent as compared to approximately 18.3 percent in 
plots sampled in prairie habitat in Colorado. Of the total montane 
habitat, approximately 85 percent occurs in Colorado.

Arizona

    In 2007, occupied habitat on non-Tribal lands in Arizona comprised 
approximately 108,570 ac (40,500 ha) (Underwood 2007, p. 30). No 
comprehensive data are available from Tribal lands in Arizona, which 
include 50 percent of the Statewide potential habitat. Therefore, the 
2007 estimate for Arizona (Underwood 2007, p. 30) is likely 
substantially less than what actually exists. Due to a lack of any 
Tribal estimates since 1961, recent population trends on Tribal lands 
statewide are unknown, but may have increased over the 1961 estimate of 
435,419 ac (176,207 ha). We are unaware of any disproportionate adverse 
effects to the species on Tribal lands during this interval, and we 
assume that habitat trends may have followed a similar pattern as on 
non-Tribal lands. All habitat within Arizona is considered prairie.

Colorado

    The Colorado Department of Agriculture (CDA 1990, p. A-3) solicited 
questionnaire responses from farmers and ranchers from which they 
extrapolated a 1990 estimate of 1,553,000 ac (621,200 ha) of occupied 
habitat for all 3 species of prairie dogs found in Colorado 
(Gunnison's, white-tailed, and black-tailed). Based on species 
occurrence by county, Seglund et al. (2005, p. 26) estimated that 
438,876 ac (177,607 ha) were occupied by Gunnison's prairie dogs.
    From 2002 to 2005, the Colorado Division of Wildlife (CDOW) 
interviewed field personnel from CDOW, the Service, the USFS, and the 
BLM regarding the habitat occupied by Gunnison's prairie dogs in the 
State. Colonies were mapped on 1:50,000 scale U.S. Geological Survey 
county sheets and were designated as ``active'' (known to have prairie 
dogs inhabiting the colony within the last 3 years); ``inactive'' 
(prairie dogs occurred in the area but have not been present in more 
than 3 years); or ``unknown'' (prairie dogs were known to occur 
historically, but current status was unknown). From this effort, CDOW 
estimated 182,237 ac (72,895 ha) of active colonies; 9,042 ac (3,617 
ha) of inactive colonies; and 171,970 ac (68,788 ha) of colonies in 
unknown status within Colorado (CDOW 2007, p. 3). These data suggest an 
increase over the historical 1961 estimate of 115,650 ac (46,802 ha) of 
occupied habitat in Colorado. We have no way of estimating what percent 
of this difference may be due to different mapping techniques. We 
believe that the difference is mostly due to an actual increase in 
prairie dogs, likely within the prairie portion of the range, because 
data from the montane portion of the range indicate significantly 
reduced occupancy rates (see additional analysis below). We used area 
estimates from 2002 to 2005 to compute a Statewide occupancy estimate 
of 2.1 percent (known active colony area divided by area of potential 
habitat) (CDOW 2007). However, the occupancy modeling studies performed 
in 2005 and 2007 in Colorado, including both prairie and montane 
portions of the range, yielded Statewide occupancy estimates of 7.5 and 
8.6 percent, respectively (Andelt et al. 2006, p. 15; CDOW 2007, p. 
19), and these estimates are considered more reliable.

Montane and Prairie Habitat in Colorado

    Within Colorado, CDOW has designated individual population areas to 
identify where Gunnison's prairie dogs exist and where management 
activities should be focused. The montane portion of the species' range 
in Colorado is composed of the Gunnison, San Luis Valley, South Park, 
and Southeast population areas. By using CDOW (2007, p. 28) estimates 
of potential habitat, we determined that the montane range portion in 
Colorado comprises about 80 percent (6.9 million of 8.5 million ac (2.8 
million of 3.4 million ha)) of the available Gunnison's prairie dog 
habitat in the State. However, the montane range portion only contains 
about 40 percent (73,861 of 182,237 ac (29,544 of 72,894 ha)) of the 
available Gunnison's prairie dog habitat occupied in the State, based 
on our calculations using CDOW mapped area data (CDOW 2007, p. 3).
    The La Plata--Archuleta and Southwest population areas, in the 
prairie portion of Colorado's Gunnison's prairie dog habitat, comprise 
about 20 percent of the Gunnison's prairie dog habitat and contain 
about 60 percent of habitat occupied in the State (CDOW 2007, pp. 3, 
19). The higher proportion of occupied habitat in the smaller prairie 
portion of the State indicates that Gunnison's prairie dogs are more 
abundant in the prairie habitat area.

[[Page 6666]]

    The 2005 occupancy modeling studies also indicate a higher 
proportion of occupancy (16 percent) in the prairie portion of the 
range in Colorado, and a lower proportion of occupancy (3.2 percent) in 
the montane portion of the species' range in Colorado (Andelt et al. 
2006, p. 17; CDOW 2007, p. 19). When the study was repeated over the 
same plots in 2007, occupancy was again found to be higher (18.3 
percent) in the prairie portion and lower (3.6 percent) in the montane 
range portion in Colorado (CDOW 2007, p. 19).

New Mexico

    We have no current information on occupied habitat in New Mexico. 
The best available science is from Bodenchuck (1981 p. 1), who 
solicited questionnaire responses from agricultural producers in 1981. 
Respondents reported 107,574 ac (43,567 ha) of Gunnison's prairie dog 
occupied habitat. Bodenchuck (1981, p. 8) extrapolated a Statewide 
total of 348,000 ac (141,000 ha) of occupied habitat for the species. 
Oakes (2000, p. 216) questioned this extrapolation because of possibly 
faulty assumptions used to derive it. Knowles (2002, p. 22) estimated 
that 75,000 ac (30,000 ha) of occupied habitat existed in 1982. New 
Mexico Department of Game and Fish used Digital Orthophoto Quarter 
Quadrangles to estimate a minimum of 9,108 ac (3,689 ha) of occupied 
habitat Statewide in 2004 (Seglund et al. 2005, p. 23). However, this 
method appears to be hampered by inaccurate detection of disturbances, 
time elapsed since photography, time elapsed since ground mapping, 
temporal changes in prairie dog towns, and other factors (Seglund et 
al. 2005, p. 33). While these estimates have limited accuracy, general 
use in assessing Statewide occupied habitat indicates that Gunnison's 
prairie dogs appeared to be decreasing between 1961 and 2004.

Montane and Prairie Habitat in New Mexico

    New Mexico also includes both montane and prairie habitat. The 
montane habitat is geographically connected to the montane portion of 
the Gunnison's prairie dog habitat in Colorado. It comprises about 17 
percent of the Gunnison's prairie dog habitat in New Mexico; we do not 
have accurate data on total acres in New Mexico, and therefore do not 
provide an acre estimate for the montane portion. We have no data on 
the percent occupancy in this habitat.
    The prairie habitat in New Mexico comprises about 83 percent of the 
habitat; we do not have accurate data on total acres in New Mexico, and 
therefore do not provide an acre estimate for the prairie portion. We 
have no data on the percent occupancy in this habitat.

Utah

    The Utah Division of Wildlife Resources estimated that 22,000 ac 
(8,906 ha) of occupied Gunnison's prairie dog habitat existed in Utah 
in 1968 (Seglund et al. 2005, p. 35). Knowles (2002, p. 21) estimated a 
minimum of 3,678 ac (1,490 ha) of occupied habitat Statewide. The 
Statewide trend in occupied habitat appears to have decreased from 
100,000 ac (40,500 ha) in 1961 (Bureau of Sport Fisheries and Wildlife 
1961, p. 5), to 40,000 ac (16,000 ha) in 2007 (Lupis et al. 2007, p. 
3). The Gunnison's prairie dog occupancy in Utah was estimated to be 
15.7 percent in 2007 (Lupis et al. 2007, p. 3). We consider all 
Gunnison's prairie dog habitat in Utah as prairie.

Summary of Statewide Estimates of Abundance

    We have empirical data on Gunnison's prairie dog occupancy that 
indicate a large decline in rangewide occupied acres. We also have 
recent empirical data that indicates percent occupancy within two 
separate portions of the range is significantly different.
    Data on acres occupied indicate that between 1916 and the present, 
habitat occupied by Gunnison's prairie dogs throughout its range 
declined from approximately 24,000,000 ac (9,700,000 ha) to between 
340,000 and 500,000 ac (136,000--200,000 ha). This represents a 
rangewide decline of greater than 95 percent.

Summary of Factors Affecting the Species Rangewide

    Section 4 of the Act (16 U.S.C. 1533) and implementing regulations 
at 50 CFR 424, set forth procedures for adding species to the Federal 
Lists of Endangered and Threatened Wildlife and Plants. In making this 
finding, we summarize below information regarding the status and 
threats to the Gunnison's prairie dog in relation to the five factors 
provided in section 4(a)(1) of the Act.
    In making this 12-month finding, we have considered all scientific 
and commercial information received or acquired between the time of the 
initial petition (February 23, 2004) and the end of the most recent 
public comment period (October 29, 2007), and additional scientific 
information from ongoing species surveys and studies as they became 
available.
    Under section (4) of the Act, we may determine a species to be 
endangered or threatened on the basis of any of the following five 
factors: (A) Present or threatened destruction, modification, or 
curtailment of habitat or range; (B) overutilization for commercial, 
recreational, scientific, or educational purposes; (C) disease or 
predation; (D) inadequacy of existing regulatory mechanisms; or (E) 
other natural or manmade factors affecting its continued existence. We 
evaluated whether threats to the Gunnison's prairie dog may affect its 
survival. Our evaluation of threats, based on information provided in 
the petition, available in our files, and available in published and 
unpublished studies and reports, is presented below.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of its Habitat or Range

    Agricultural land conversions historically had a significant impact 
on Gunnison's prairie dog habitat (Knowles 2002, p. 12). Gunnison's 
prairie dogs have been displaced from some of the more productive 
valley bottomlands in Colorado and New Mexico (Longhurst 1944, p. 36). 
Agriculture currently impacts 2,063,930 ac (834,243 ha), or less than 
three percent, of the Gunnison's prairie dog range (Seglund et al. 
2005, p. 43). Seglund et al. (2005, p. 41) indicate agriculture is not 
a major rangewide threat because of the small percentage of the range 
affected, but also because agriculture provides highly productive 
forage in place of the native arid landscape. Current adverse impacts 
relate to secondary actions at a local scale, such as prairie dog 
control (for example, poisoning, shooting) in areas where prairie dogs 
occupy lands used for agriculture, particularly private lands. We 
assess shooting under Factor C, poisoning under Factor E, and both in 
Factor D.
    Urbanization also has caused habitat loss for Gunnison's prairie 
dog. Seglund et al. (2005, p. 41) determined that urbanization affects 
577,438 ac (233,681 ha) within the range of the species (less than two 
percent of the range). However, it appears this analysis considered 
only the direct effects of habitat loss. Urbanization also exerts 
indirect effects (for example, poisoning and shooting of prairie dogs), 
extending a human ``disturbance zone'' outward from the actual 
development footprint.
    Lower-density suburban development occurring in the southern Rocky 
Mountains is scattered and results in a fragmenting of habitats. In 
Colorado, urban development on the west slope of the Rocky Mountains 
(montane habitat) is occurring rapidly; 38 percent of Gunnison's 
prairie dog range is predicted to be impacted by low urban development 
(less than 40 units per ac;

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99 per ha), 6 percent by moderate development (40 to 80 units per ac; 
99 to 198 per ha), and 5 percent by high development (fewer than 80 
units per ac) between 2000 and 2020 (CDOW 2007, p. 28). We do not have 
information on the extent of development projected to occur in the 
other States within the species' range (Utah, Arizona, and New Mexico). 
Potential threats to Gunnison's prairie dog populations due to urban 
and suburban development exist, but have not been quantified, in the 
four cities of Santa Fe and Albuquerque, New Mexico; Flagstaff, 
Arizona; and Gunnison, Colorado (CDOW 2007, p. 4). In some areas, 
Gunnison's prairie dogs threatened by urban development have been 
captured and relocated to preserves or other nearby habitats, 
mitigating effects to overall population numbers, but not to area of 
habitat.
    Although urban and suburban development exert adverse impacts on 
Gunnison's prairie dog populations at a local scale, they likely affect 
less than three percent of the species' range; low density development 
appears to be compatible with continued use by prairie dogs, due to the 
offsets provided by lawns and pastures that provide high quality forage 
(Seglund et al. 2005, p. 41).
    Noxious weeds can increase in the presence of livestock 
overgrazing, and a relationship likely exists between overgrazing, 
Bromus tectorum (cheat grass) proliferation, and increased fire 
frequency and intensity (Seglund et al. 2005, p. 43). However, we have 
no data that quantifies these factors or their correlation with effects 
to Gunnison's prairie dog populations. The impact of overgrazing on 
prairie dog populations is contradictory. Some reports have noted that 
species density is positively correlated with the number of native 
plants (Slobodichikoff et al. 1988, p. 406), and that grazing has 
decreased forage availability (Seglund et al. 2005, p. 42). Other 
reports have concluded that prairie dog density is positively 
correlated with an increase in grazing, which simulates the shortgrass-
type of prairie environment preferred by prairie dogs (Fagerstone and 
Ramey 1996, p. 88; Marsh 1984, p. 203, Slobodchikoff et al. 1988, p. 
406). Considering the conflicting conclusions of published literature, 
and the lack of large-scale population decreases due to habitat 
alterations from livestock grazing, we find this is not a significant 
threat to the Gunnison's prairie dog.
    Numerous land parcels within the Gunnison's prairie dog range are 
leased for oil and gas development (Seglund et al. 2005, pp. 36, 42). 
However, no information is available that quantifies the amount of 
occupied habitat affected. In a study of white-tailed prairie dogs, 
Menkens and Anderson (1985, p. 13) concluded that any impact from 
seismic testing is negligible. However, we acknowledge that oil and gas 
development is rapidly occurring (Seglund et al. 2005, p. 44), and that 
this potential threat should be considered more closely when more 
accurate data are available.
    Road-related Gunnison's prairie dog mortality exists in proximity 
to specific population areas. Roads may be increasing due to oil and 
gas development. However, no studies quantify road mortality of 
Gunnison's prairie dogs. We have no data indicating that roads are 
currently threatening the species rangewide, and we conclude that 
prairie dog populations are able to recover from individual losses due 
to road mortality.
    Conservation principles indicate that smaller, more isolated 
populations are more vulnerable to extirpation (Barnes 1993, p. 34; 
Cully 1993, p. 43; Fitzgerald 1970, p. 78; Gilpin and Soule 1986, pp. 
30-31; Miller et al. 1994, p. 151; Mulhern and Knowles 1995, p. 21; 
Wilcox and Murphy 1985, p. 883; Wuerthner 1997, p. 464). Lomolino et 
al. (2003, p. 116) found that persistence of Gunnison's prairie dog 
colonies increased significantly with larger colony size and decreased 
isolation. However, we found no studies or data that specifically 
assess the magnitude of the threats discussed under Factor A 
(agriculture land conversions, urbanization, grazing, roads, and oil 
and gas leasing) and resulting fragmentation throughout the range of 
Gunnison's prairie dog habitat.

Summary of Factor A

    After assessing the best available science on the magnitude and 
extent of the effects of agricultural land conversion, urbanization, 
grazing, roads, oil and gas development, and fragmentation of habitat, 
we find that the destruction, modification, and curtailment of 
Gunnison's prairie dog's habitat or range are not significant threats. 
Agriculture, urbanization, roads, and oil and gas development each 
currently affect a small percentage of Gunnison's prairie dog habitat. 
Effects of livestock grazing, while widespread, have not resulted in 
measurable population declines. However, we need more information on 
the impacts of fragmentation and isolation with regard to persistence 
of prairie dog populations and on the magnitude of the potential threat 
posed by increasing oil and gas development.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Gunnison's prairie dogs have been historically subjected to 
recreational shooting and shooting as a form of pest management on 
ranch and agricultural land; these practices continue under current 
State regulations (see Factor D. Inadequacy of Existing Regulatory 
Mechanisms). Prairie dogs are especially vulnerable to shooting due to 
their colonial behavior, which facilitates easy access to many 
individuals at once (Seglund et al. 2005, p. 48). Most field studies on 
the effects of shooting prairie dogs have been carried out on black-
tailed prairie dogs, but we consider the results relevant to Gunnison's 
prairie dogs (CDOW 2007, p. 41). Shooting effects include population 
reduction and alteration of behavior, such as decreased foraging rates 
and increased vigilance, which reduce individual prairie dog vigor and 
result in lower reproductive output (Knowles 1988, p. 54; Reeve and 
Vosburgh in press, p. 5; Vosburgh 1996, pp. 32-33; Vosburgh and Irby 
1998, p. 368; Pauli and Buskirk 2007, pp. 1223-1224).
    Recreational shooting can reduce prairie dog population density at 
specific sites (Knowles 2002, p. 14; Miller et al. 1993, p. 91; 
Vosburgh 1996, pp. 13-14; Vosburgh and Irby 1998, pp. 366-367). Local 
extirpation of colonies may have occurred in isolated circumstances in 
the past (Knowles 1988, p. 54). However, increased population growth 
rates or recovery from very low numbers following shooting also have 
been reported (Knowles 1988, p. 54; Reeve and Vosburgh in press, p. 7). 
Recent studies of the effects of shooting on black-tailed prairie dogs 
appear to contradict the idea that populations quickly rebound from 
shooting. Reproductive output on colonies subjected to shooting 
decreased by 82 percent, while control colonies maintained a stable 
reproductive rate over the same period (Pauli and Buskirk 2007, p. 
1228). Therefore, black-tailed prairie dogs do not appear to rebound 
quickly from shooting.
    The International Union for the Conservation of Nature/Species 
Survival Commission (IUCN/SSC) Conservation Breeding Specialist Group 
evaluated the effects of shooting mortality on population viability of 
Gunnison's prairie dogs (CDOW 2007, p. 124). Simulations were run with 
a shooting closure in place from March 1 through June 14 each year 
(approximating State closures) and without any closures. Having the 
closure in place resulted in positive population growth and

[[Page 6668]]

negligible risk of extinction, except in scenarios with the highest 
levels (20 percent) of shooting-based mortality. Simulations run 
without the seasonal shooting closure in place suggest that when 
initial population sizes are smaller (less than 250 individuals) and 
shooting mortality is high (20 percent), a decrease in growth rate and 
an increase in population extinction risk exist (CDOW 2007, pp. 135-
137). Colorado, Utah, and Arizona (outside Tribal lands) have 
implemented seasonal closures on prairie dog shooting. In Arizona and 
New Mexico, the Navajo Nation monitors this threat but currently 
implements no closures on shooting because it finds the level of 
shooting to be low on its lands (Cole 2007, p. 4).

Summary of Factor B

    We have determined that shooting continues to be a threat to the 
Gunnison's prairie dog throughout all of its range and contributes to 
the decline of the species when combined with the effects of disease 
(see Factor C below). However, this threat is being monitored and 
managed in all States and the Navajo Nation, and modeling results 
suggest seasonal shooting closures implemented in Colorado and Arizona 
will likely reduce population-level losses. Therefore, we have 
determined that overutilization for commercial, recreational, 
scientific, or educational purposes is not a significant threat to the 
Gunnison's prairie dog.

C. Disease or Predation

    While prairie dogs are prey to numerous species, including coyotes, 
badgers, black-footed ferrets, and various raptor species, there is no 
information available to indicate that predation has an overall adverse 
effect on the species. Black-footed ferrets have been reintroduced into 
two locations in Arizona, including the Aubrey Valley, where Gunnison's 
prairie dog populations appear to be stable.
    The Gunnison's prairie dog is, however, affected by sylvatic 
plague, which occurs in regular outbreaks and causes population 
declines and extirpations. Plague is an exotic disease foreign to the 
evolutionary history of North American species (Barnes 1982, p. 238; 
Barnes 1993, p. 29; Biggins and Kosoy 2001, p. 907). This flea-borne 
disease, caused by infection with the bacterium Yersinia pestis, is 
shared by humans and other vertebrate animals. Rodents are the primary 
vertebrate hosts of Y. pestis, but other mammals can be infected. Y. 
pestis is transmitted to mammals by bites of infected fleas, direct 
contact with infected animals, and rarely by inhalation of infectious 
respiratory droplets from another animal (Gage et al. 1995, pp. 695-
696). Plague was first observed in wild rodents (termed sylvatic 
plague) in North America near San Francisco, California, in 1908 and 
was detected in Gunnison's prairie dogs in the 1930s (Eskey and Hass 
1940, p. 6). Plague has subsequently spread so that it now encompasses 
the entire range of the species (Centers for Disease Control 1998, p. 
1; Cully 1989, p. 49; Girard et al. 2004, p. 8408). Therefore, it has 
only been present within the species' range for approximately 70 years, 
allowing very little time for any resistance to evolve (Biggins and 
Kosoy 2001, p. 913). Once established in an area, plague becomes 
persistent and periodically erupts, with the potential to eventually 
extirpate or nearly extirpate entire colonies (Barnes 1982, p. 255; 
Barnes 1993, p. 28; Cully 1989, p. 51; Cully et al. 1997, p. 711; 
Fitzgerald 1993, pp. 52-53). The term ``enzootic'' describes plague 
existing at a less severe level, sometimes referred to as a 
``maintenance'' condition, that is present continuously throughout a 
species' habitat; the term ``epizootic'' describes a severe plague 
outbreak or amplification transmission cycle (Gage et al. 1995, p. 
696).
    Prairie dogs are highly susceptible to plague, and this 
susceptibility is thought to be a function of high population 
densities, abundant flea vectors, and uniformly low resistance (Biggins 
and Kosoy 2001, p. 913). Gunnison's prairie dogs can experience 
mortality rates of greater than 99 percent during epizootics, and 
eradication of populations can occur within one active season 
(Lechleitner et al. 1962, pp. 190-192; Lechleitner et al. 1968, p. 736; 
Rayor 1985, p. 194; Cully 1989, p. 49).
    Oral vaccination through consumption of vaccine-laden baits could 
reduce mortality from plague. Mencher et al. (2004, pp. 5504-5505) 
report protection against plague in black-tailed prairie dogs, elicited 
through voluntary consumption of a vaccine-laden bait in the 
laboratory. The vaccine has been shown to be safe in numerous animals 
including black-footed ferrets, raccoons, skunks, bobcats, cats, dogs, 
and sheep. However, future field trials are required to test the 
efficacy on the Gunnison's prairie dog.
    Recovery rates of Gunnison's and Utah prairie dog colonies studied 
2 years post-epizootic found that Gunnison's prairie dog colonies 
experienced 100 percent mortality and remained depopulated throughout 
the study due to the lack of available immigrants (Turner 2001, p. 14). 
Partial or complete recovery following population reductions due to 
plague have been reported for both white-tailed and black-tailed 
prairie dogs (Cully 1993, pp. 40-41), but little to no recovery has 
been noted in montane Gunnison's prairie dog colony die-offs, even 
after long periods of time (Capodice and Harrell 2003, pp. 5-7; Cully 
et al. 1997, p. 717; Lechleitner et al. 1968, p. 734). Possible long-
term consequences of continued plague infection in Gunnison's prairie 
dog populations may be:
    (1) local extirpation of colonies;
    (2) reduced colony size;
    (3) increased variance in local population sizes, and
    (4) increased inter-colony distances (CDOW 2007, p. 43).
    The factors that influence interspecific (between species) 
transmission of plague from mammalian or avian reservoirs (for example, 
coyotes, raptors, corvids) into prairie dog populations are unclear, 
but seem to be primarily through fleas that could increase in moister 
climates (Parmenter et al. 1999, p. 818; Rayor 1985, p. 195). However, 
interspecific transmission does not seem to be a significant factor 
creating plague epizootics. Plague is now considered enzootic 
throughout the range of the Gunnison's prairie dog.
    The primary factor influencing plague enzootics in Gunnison's 
prairie dogs is thought to be abundance of fleas within their own 
colonies. This appears to be correlated with seasonal moisture in 
specific habitat areas. Plague outbreaks may be triggered by climatic 
conditions, such as mild winters and moist springs (Parmenter et al. 
1999, p. 818; Rayor 1985, p. 195). Enscore et al. (2002, p. 191) found 
a close relationship between human plague cases in the southwestern 
United States and high amounts of late spring (February to March) 
precipitation (time-lagged 1 and 2 years) and maximum daily summer 
temperature values in the moderately high range (85 to 90 [deg]F; 29 to 
32 [deg]C).
    Girard et al. (2004, p. 8408) postulated that when resistant hosts 
of plague encounter a susceptible species that is plague na[iuml]ve and 
has a high population density, an epizootic occurs. During epizootic 
phases, declines in abundance of susceptible species like prairie dogs 
are observed (Hanson et al. 2007, p. 790). The rapid dispersal of the 
pathogen through an area can be followed by an enzootic phase, a slower 
transmission cycle that disperses through the lower-density, more 
resistant hosts remaining from the first cycle. This establishes the 
disease in stable reservoirs for future emergence

[[Page 6669]]

(Girard et al. 2004, p. 8413; Gage and Kosoy 2005, pp. 506-509).
    Enzootic infection is generally considered characteristic of a 
stable rodent-flea infectious cycle where host rodents are relatively 
resistant to the disease. However, Hanson et al. (2007, p. 792) found 
that an unexpectedly high percentage of black-tailed prairie dog 
colonies in Montana tested positive for plague. They speculate that, 
under some conditions, black-tailed prairie dogs, rather than acting as 
resistant hosts, may serve as enzootic hosts or carriers of the 
pathogen. Plague antibody titers (concentrations in blood) have been 
found in small numbers of Gunnison's prairie dogs in New Mexico, 
indicating individual exposure to plague and subsequent recovery (Cully 
et al. 1997, p. 717; Cully and Williams 2001, p. 898). Plague appears 
to have had little effect on a Gunnison's prairie dog population in 
Aubrey Valley, Arizona (Wagner and Van Andelt 2007, p. 2). However, 
little evidence of resistance to plague has been found in any species 
of prairie dog at this time.
    In conducting a Population Viability Analysis on Gunnison's prairie 
dogs, the IUCN/SSC Conservation Breeding Specialist Group (CDOW 2007, 
p. 123) hypothesized that in an enzootic scenario, plague operates at a 
relatively low level each year, thereby increasing average annual rates 
of mortality above what would occur in a more benign non-enzootic 
scenario.
    Gunnison's prairie dog populations are more susceptible to decline 
from plague than white-tailed prairie dog populations and are at least 
as, if not more, susceptible than black-tailed prairie dog populations 
(Antolin et al. 2002, p. 14; Cully 1989, p. 51; Cully and Williams 
2001, p. 899; Hubbard and Schmitt 1983, p. 51; Knowles 2002, p. 13; 
Ruffner 1980, p. 20; Torres 1973, p. 31; Turner 2001, p. iii). 
Gunnison's prairie dogs commonly forage outside of their home 
territory, a characteristic that may play a significant role in the 
susceptibility of the species to plague. The Gunnison's prairie dog may 
be more susceptible to plague than the black-tailed prairie dog because 
of the Gunnison's less exclusive territorial behavior (many mix 
relatively freely throughout adjacent territories) and thereby 
contribute to the communicability of plague (Hoogland 1999, p. 8).
    The Gunnison's prairie dog is also likely more susceptible to 
plague than the white-tailed prairie dog because the Gunnison's 
typically occurs at higher densities and is less widely dispersed on 
the landscape, allowing for more frequent transmission of the disease 
from one individual to another (Antolin et al. 2002, p. 19; Cully 1989, 
p. 49; Cully and Williams 2001, p. 901; Turner 2001, p. 31). Biggins 
(2003, p. 6) speculated that if transmission rates for plague are at 
least partly dependent on host density, prairie dog populations on good 
quality sites may undergo both larger declines and more rapid 
recoveries than those on poor sites.
    Available literature is inconclusive regarding whether isolation or 
density of a colony affects the number and frequency of plague 
outbreaks. Lomolino et al. (2003, p. 118) and others (Cully and 
Williams 2001, p. 901; Miller et al. 1993, pp. 89-90) suggested that 
isolation and fragmentation may provide some protection to prairie dogs 
from plague by lessening the likelihood of disease transmission. 
However, this theory no longer applies when plague is enzootic 
throughout the range of Gunnison's prairie dog (as it appears to be), 
in which case isolation of colonies reduces the chance of 
recolonization after extirpation (Wagner and Drickamer 2002, p. 16; 
Lomolino and Smith 2001, pp. 942-943). In areas where Gunnison's 
prairie dog colonies are located close to each other (less than 6 miles 
(mi) (10 kilometers (km) apart), inter-colony dispersal of plague is 
likely through infected prairie dogs (Girard et al. 2004, p. 8412). For 
colonies separated by long distances or unsuitable habitats, infection 
may occur due to long-distance dispersal of plague-infected fleas by 
domestic dogs, coyotes, raptors, or other predators and scavengers 
(Barnes 1993, p. 34), or plague may already persist as enzootic 
throughout Gunnison's prairie dog range.
    The impacts of plague outbreaks, which lead to the loss of prairie 
dog colonies of all sizes (Roach et al. 2001, p. 956), are magnified by 
isolation of colonies. Colony growth after an epizootic is mainly the 
result of recolonization by inter-colony dispersers (Antolin et al. 
2002, p. 17). Wagner et al. (2006, pp. 334-335) studied cycles of 
extirpation and recolonization in Gunnison's prairie dogs in Arizona, 
including a large number of colonies over a large geographic area, and 
found a significant relationship between the persistence of colonies 
and the persistence of their nearest neighboring colony. Increased 
isolation decreases the likelihood of recolonization following a plague 
outbreak if the distance between the infected colony and the next 
nearest colony is beyond the dispersal capabilities of the species. For 
example, Lechleitner et al. (1962, pp. 195, 197) documented a 1959 
plague outbreak in a Gunnison's prairie dog colony in Colorado that 
killed all members of the colony. Prior to the outbreak, this colony 
had been continuously occupied for 20 years, despite several poisoning 
attempts. Two years after the plague outbreak, the colony still had not 
been recolonized, likely because it was isolated from other colonies by 
8 mi (13 km) (Lechleitner et al. 1962, p. 187).
    Research is underway on the efficacy of insecticides in protecting 
various prairie dog species from plague. Biggins and Godby (2005, p. 2) 
hypothesized that if enzootic plague is affecting populations of 
prairie dogs, an ambitious effort to remove the disease should result 
in increased survival rates of prairie dogs. Fleas in Utah prairie dog 
burrows were effectively controlled by annual treatments of the 
insecticide deltamethrin; fleas were reduced 96 to 98 percent within 
one month of treatment (Biggins and Godby 2005, p. 5). Studies of the 
effects of flea control on black-tailed and white-tailed prairie dogs 
have shown similar results (Biggins 2007). At this time, chemical 
dusting of individual prairie dog burrows is labor intensive and 
expensive.
    All recent, major Gunnison's prairie dog colony declines documented 
in published literature have been attributed to plague epizootics. 
However, the magnitude of the plague threat appears to be different in 
the montane and prairie portions of the Gunnison's prairie dog range. 
Population declines in prairie habitat are less dramatic than those in 
montane habitat; partial recovery or establishment of new colonies have 
been documented following plague in the prairie range portion, but are 
rare or absent following plague outbreaks in the montane range.
    We reviewed literature on the status of Gunnison's prairie dog 
populations within the two portions of the range and, specifically, all 
published and unpublished literature on the effects of plague on 
prairie dogs. While some studies were not recent, summarizing them 
below provides background on the responses of Gunnison's prairie dog 
populations to plague in each portion of the range.

Effects of Plague in Montane Habitat

    Several well-studied colonies within the montane portion of the 
Gunnison's prairie dog range have been documented as being extirpated, 
or nearly so, due to plague. The South Park, Colorado, population area 
included estimated occupied habitat of 915,000 ac (371,000 ha) in 1945; 
74,000 ac (30,000 ha) in 1948; and 42 ac (17 ha) in 2002 (CDOW

[[Page 6670]]

2007). This decline was largely due to plague and affected a 
substantial portion of the species' extant occupied habitat in Colorado 
(at least 15 percent). A plague event in Saguache County, Colorado, 
that progressed across seven colonies in 2 years left only scattered 
individuals surviving in two colonies (Lechleitner et al. 1968, p. 
734). In Gunnison, Saguache, and Montrose Counties, Colorado, plague 
also was responsible for a decline from 15,569 ac (6,228 ha) of 
occupied habitat in 1980, to 770 ac (308 ha) in 2002 (note that 
Montrose County is in the Southwest population area in prairie habitat) 
(Capodice and Harrell 2003, pp. 5-7). A complete die-off of a colony 
due to plague in Chubbs Park, Chaffee County, Colorado, occurred in 
1959 (Lechleitner et al. 1962, p. 185). In August 1958, the population 
was stable and healthy, but in 1959 an epizootic spread 2 mi (3 km) 
within 3 months; prairie dogs continued to be absent from the area in 
1960 and 1961, and we have no recent information on the existence of 
prairie dogs in that location. Plague resulted in the complete loss, 
over a 2-year period, of a colony in South Park, Colorado (Fitzgerald 
1970, pp. 68-69).
    Approximately 1,000 to 1,500 Gunnison's prairie dogs were killed by 
an outbreak of plague in a 148-ac (60-ha) colony in Curecanti National 
Recreation Area near Gunnison, Colorado, in 1981 (Rayor 1985, p. 194). 
A few animals survived the disease and Gunnison's prairie dogs were 
again abundant in the area in 1986 (Cully 1989, p. 49). In 2002, 252 ac 
(102 ha) of habitat in the Recreation Area were occupied by Gunnison's 
prairie dog colonies (Capodice and Harrell 2003, p. 23), but the 
current estimate is 12 ac (4.8 ha) (Childers 2007, p. 2). Colonies 
within the Recreation Area experienced six plague epidemics between 
1971 and 2007. Of the 9 historic Gunnison's prairie dog colonies, 3 are 
currently active, and 2 act as source populations for the main prairie 
dog concentration area (Childers 2007, p. 1). If the source colonies 
die off due to plague, repopulation may not be possible because any 
other Gunnison's prairie dog populations remaining will be separated by 
distance (more than 6 mi (10 km)) and impassable geographical features 
such as rivers and mountains (Lomolino et al. 2003, p. 116; Pizzimenti 
and Hoffman 1973, p. 1).
    Recently, plague has been implicated in the loss of several large 
colonies on BLM land within the Gunnison population area (CDOW 2007, p. 
4). A large colony southeast of Gunnison, Colorado, that was very 
active in 2005, was totally devoid of prairie dogs in 2006 and 2007. 
Four other large colonies in the same vicinity were active in 2006, but 
by 2007, no prairie dog activity was observed. Plague is the suspected 
cause of these extirpations, because of the complete elimination of the 
prairie dogs with no sign of poisoning (CDOW 2007, p. 4).
    Fitzgerald (1993, p. 52) expressed concern about the status of the 
Gunnison's prairie dog in Colorado, indicating that plague had 
eliminated many populations, including almost all of the populations in 
South Park. He also suggested that populations appeared to be in poor 
condition in the San Luis Valley, and were extirpated from the extreme 
upper Arkansas River Valley, as well as Jefferson, Douglas, and Lake 
Counties. These areas comprise most of the Gunnison's prairie dog 
montane habitat in Colorado.
    During 1984 through 1987, a plague event reduced the population of 
Gunnison's prairie dogs in the Moreno Valley of New Mexico from more 
than 100,000 individuals to between 250 and 500, a decline of greater 
than 99 percent (Cully et al. 1997, pp. 708-711). Although the growth 
rate of the remaining population increased following the epizootic, 
another plague event swept through the area in 1988, and the population 
in July 1996 was still ``a fraction'' of what it had been in 1984 
(Cully et al. 1997, p. 718).
    Occupancy modeling performed in Colorado in 2005 indicated a lower 
proportion of occupancy in the montane portion of the species' range 
within Colorado (3.2 percent) than in the prairie portion within 
Colorado (16.0 percent) (Andelt et al. 2006, p. 17; CDOW 2007, p. 19). 
When the study was repeated over the same plots in 2007, occupancy was 
again found to be lower (3.6 percent) in the montane range portion in 
Colorado than in the prairie portion (18.3 percent) (CDOW 2007, p. 19). 
The only recent threat responsible for whole population declines and 
extirpations, as documented in the studies cited in this section, is 
plague.
    The frequency of plague epizootics appears to be high in montane 
habitat due to moister environmental conditions that are conducive to 
greater flea densities. The impact of plague epizootics in montane 
habitat is great because the small, isolated populations cannot 
recolonize. Within the South Park, Gunnison, and Southeast montane 
population areas in Colorado, no prairie dog complexes that approach a 
size considered sustainable exist, and only a few small complexes exist 
within the San Luis Valley population area (CDOW 2007, pp. 1-17). 
Without a metapopulation structure, an overall decline in persistence 
takes place (Lomolino and Smith 2001, p. 942).
    The landscape status in the montane portion of Gunnison's prairie 
dog range is characterized by fewer, smaller colonies that are 
isolated, and few to no complexes or metapopulation structure. 
Isolation of populations is related to the montane geography in this 
portion of the range. Gunnison's prairie dogs occupy low valleys and 
mountain meadows within this habitat (Seglund et al. 2005, p. 12), 
likely because the short growing season at elevations higher than 
10,000 ft (3,048 m) limits forage (Andelt et al. 2006, p. 17). In 
addition, mountain topography minimizes the zone of contact between 
populations (Knowles 2002, p. 3). At least four mountain ranges within 
the montane portion of the range act as barriers to Gunnison's prairie 
dog dispersal (Pizzimenti and Hoffman 1973, p. 1). These factors make 
the prairie dogs in this habitat highly susceptible to plague-related 
declines, and we have no evidence of long-term recovery from plague in 
the montane habitat area.

Effects of Plague in Prairie Habitat

    The Southwest and the La Plata-Archuleta populations in Colorado 
are within the prairie portion of Gunnison prairie dog range. The 
Southwest population comprises the largest population of Gunnison's 
prairie dogs in Colorado, with an estimated 88,267 ac (35,307 ha) of 
active colonies. Currently, prairie dogs can be found in nearly any 
habitat suitable for occupation, although densities are low to very low 
in native rangeland areas. Plague may be a problem in this area, 
because periodic die-offs not associated with poisoning or other 
control measures have been noted by local farmers and ranchers in the 
past. However, unlike populations in montane habitat within Colorado, 
these populations appear to rebound from periodic epizootics (CDOW 
2007, p. 16).
    Populations in the La Plata-Archuleta population area appear to 
undergo plague outbreaks every 4 to 7 years, which may be limiting some 
populations (CDOW 2007, p. 7). Occupancy modeling in 2005 and 2007 
documented Gunnison's prairie dog occupancy of 17.6 percent and 27.0 
percent, respectively, in the Southern Ute Reservation (part of the La 
Plata-Archuleta population area), and 15.6 percent and 16.3 percent in 
the Southwest area (CDOW 2007, p. 19). The persistence of these 
populations, while undergoing repeated plague outbreaks, is likely due 
to their proximity to other populations within the prairie portion of 
the species' range

[[Page 6671]]

and immigration from those populations.
    In Arizona, from 1987 to 2001, an estimated 68 percent reduction in 
the number of active Gunnison's prairie dog colonies occurred, 
primarily due to outbreaks of plague (Underwood 2007, p. 18; Wagner and 
Drickamer 2002, p. 15). However, in the area known as the Coconino 
Plateau, the area occupied by Gunnison's prairie dogs increased from 
2,126 ac (860 ha) in 1992 to 40,942 ac (16,569 ha) in 2007 (Van Pelt 
2007, p. 3), suggesting the species can withstand large plague 
epizootics through colony expansion or recolonization from nearby 
colonies. In addition, the Aubrey Valley Complex (in northwestern 
Arizona, the westernmost part of the species' range) has remained 
stable since at least 1974, despite the presence of plague, and the 
size of this complex increased from approximately 30,000 ac (12,000 ha) 
in 1997 (Underwood 2007, p. 23), to 40,000 ac (16,800 ha) in 2005 (Van 
Pelt 2005, p. 2), to 47,785 ac (19,338 ha) in 2007 (Van Pelt 2007, p. 
2). Gunnison's prairie dogs at this site had significantly higher 
levels of antigens associated with disease-causing pathogens such as 
plague, the same immune response expected if the prairie dogs had been 
vaccinated against plague (Wagner and Van Andel 2007, p. 2).
    Of 293 colonies surveyed within Gunnison's prairie dog range in 
Arizona outside of Tribal lands, 57 (19 percent) experienced die-offs 
during the summers of 2000 and 2001 (Wagner and Drickamer 2002, p. 13). 
Plague was confirmed as the causative agent for 15 of these 57 colonies 
but is thought to be the likely cause for them all, because it is the 
only disease that causes outbreaks with high mortality in prairie dogs 
(Barnes 1993, p. 34; Wagner and Drickamer 2002, p. 13). During surveys, 
they also identified the approximate boundaries of two previous plague 
outbreaks (Wagner and Drickamer 2002, p. 14).
    An outbreak occurred over approximately 1,120 square mi (2,900 
square km) west of the town of Dilkon, Arizona, on the Navajo Indian 
Reservation. This outbreak probably occurred in 1995 or 1996 (Wagner 
and Drickamer 2004, p. 14). Previous surveys in the area documented 45 
colonies on 8,649 ac (3,500 ha). Reexamination of these colonies in 
2000 and 2001 showed that all but two colonies were inactive. At most 
of the inactive colonies, burrow entrances were completely closed, and 
only mounds indicated where they formerly occurred.
    An outbreak occurred east of the town of Seligman, Arizona, across 
approximately 425 square mi (1,100 square km) around 1996. The Arizona 
Game and Fish Department conducted surveys in this area between 1990 
and 1994, and identified 47 active colonies that covered approximately 
8,649 ac (3,500 ha). In 1996, die-offs were observed in this area, and 
the U.S. Centers for Disease Control and Prevention confirmed plague as 
the cause. Although prairie dog numbers were increasing again in 1998, 
surveys in 2001 indicated that only 11 of the 47 colonies were active. 
Possibly another, undocumented, plague outbreak occurred in 1999 or 
2000, again reducing the number of individuals (Underwood 2007, p. 19). 
Despite this persistent plague activity, Gunnison's prairie dogs are 
becoming reestablished in some areas within the boundaries of the 
Seligman outbreak (Wagner and Drickamer 2002, pp. 14-15). This apparent 
resiliency is most likely due to immigration from other colonies in the 
prairie portion of the species' range.
    Plague cycles have been observed in Gunnison's prairie dogs in 
Utah, and populations have been known to die off and then recover 
(Lupis et al. 2007, p. 32). Because plague testing has not been 
conducted on Gunnison's prairie dogs in Utah, declines cannot 
definitively be attributed to the disease (Seglund et al. 2005, p. 52). 
Plague is anticipated to be an ongoing threat to Gunnison's prairie dog 
populations in Utah at both a localized, and a widespread, scale (Lupis 
et al. 2007, p. 32). The Utah Division of Wildlife Resources recently 
conducted point surveys and found that occupancy was 15.7 percent. 
Based on observed occupancy, they estimate that roughly 40,000 ac 
(16,000 ha) of southeastern Utah were inhabited by Gunnison's prairie 
dogs in 2007.
    Of 65 Gunnison's prairie dog colonies occupied prior to 1984 in 
west-central New Mexico, 32 (49 percent) were still occupied in 2005 
(Luce 2005, p. 4). The active colonies were estimated to cover 5,997 ac 
(2,399 ha) (Luce 2005, p. 5). The New Mexico Department of Game and 
Fish recently initiated occupancy modeling surveys similar to those 
used by CDOW and the Utah Division of Wildlife Resources; however, we 
currently have no data from that effort.

Summary of Factor C

    The studies cited above document the serious impact that plague has 
on Gunnison's prairie dogs. Although plague antibody titers have been 
found in a few individuals, periodic epizootic plague events generally 
kill more than 99 percent of an affected population. Whether individual 
populations recover from these epizootics depends on two main factors: 
(1) The availability of other source populations to recolonize an area; 
and (2) the frequency of epizootic outbreaks, which can reduce 
population numbers more quickly than individual prairie dogs from 
neighboring colonies can recolonize.
    Populations in the more mesic montane areas of Gunnison's prairie 
dog range appear to have been widely and severely affected by plague. 
This may be partly due to climatic conditions such as higher levels of 
spring moisture, which has been shown to increase flea numbers, and in 
turn, plague outbreaks. Isolation of prairie dog populations does not 
seem to protect them from the spread of plague, because it appears that 
plague exists with all parts of the range at some level, and can be 
spread by wider-ranging animals. The case studies cited in this section 
indicate that large populations have been repeatedly affected by plague 
and have shown no substantial recovery over long periods of time--
decades in some cases. This has left smaller, more scattered 
populations throughout the montane range portion and a complete lack of 
metapopulation structure, with the result that areas affected by plague 
are less likely to be recolonized by nearby populations. While little 
information is currently available on prairie dog movement within this 
montane habitat, its geography (populations are located in valleys 
between mountainous areas) probably impedes the ability of prairie dogs 
to recolonize populations. Within this geographic area, CDOW found 
slightly more than 3 percent occupancy of surveyed plots.
    Although documented population declines due to plague outbreaks 
also occur in the more xeric prairie portions of Gunnison's prairie dog 
range, evidence shows that many of these populations recover more 
rapidly from plague epizootics, probably due to the availability of 
nearby colonizers. This portion of the range has maintained a 
metapopulation structure that provides source populations for plague-
affected populations. The largest population in Arizona, Aubrey Valley 
in the driest portion of the range, has been increasing in recent years 
and shows indications of exposure to plague without the devastating 
effects observed elsewhere. The CDOW data documents approximately 18 
percent occupancy within prairie habitat in Colorado. Studies in Utah 
and west-central New Mexico indicate a historic decline in habitat 
occupancy of approximately 50 percent (Wright 2007, p. 3; Luce 2005, p. 
4), and a greater decline in Arizona (Wagner and Drickamer 2002, p. 
11). While this is significant, it is far less

[[Page 6672]]

than the declines seen in the montane habitat area; in addition, 
metapopulation structure continues to exist, and at least one 
Gunnison's prairie dog complex (Aubrey Valley, Arizona) is exhibiting 
some resistance to plague epizootics.
    The impacts of plague appear to be ongoing with moderate 
population-level effects when assessed across the entire range of the 
Gunnison's prairie dog. Within the prairie portion of the range, plague 
has reduced the number of populations, and is reducing the size of 
populations, but has not decimated the existing metapopulation 
structure. Gunnison's prairie dog colonies in prairie habitat exhibit 
rebound and recovery from plague epizootics in many population areas 
due to availability of animals from adjacent colonies. So far, plague 
has resulted in moderate effects to the species in the prairie portion 
of the range.
    Within the montane portion of the range, plague has significantly 
reduced the number and size of populations, resulting in high effects 
to the species. Populations within montane habitat have three distinct 
disadvantages in resisting the effects of plague:
    (1) A higher frequency of epizootics due to the moister montane 
climate that is conducive to higher abundance of fleas that spread 
plague;
    (2) smaller populations that cannot recover in numbers from plague 
epizootics; and
    (3) isolated populations and no metapopulation structure, due to 
reduced population sizes from past plague epizootics and montane 
geography, and therefore a significantly limited ability to recolonize.
    After assessing the best available science on the magnitude and 
extent of the effects of plague, we find that the impact of plague in 
the montane portion of the Gunnison's prairie dog range is significant. 
However, plague does not rise to a level of being a significant threat 
to the Gunnison's prairie dog throughout its range.

D. Inadequacy of Existing Regulatory Mechanisms

Local Laws and Regulations

    Approximately 22 percent of potential Gunnison's prairie dog 
habitat occurs on private lands, and another 30 percent occurs on 
Tribal lands or lands managed by the Bureau of Indian Affairs (Seglund 
et al. 2005, p. 21). We are not aware of any city, or county ordinances 
that provide for protection or conservation of the Gunnison prairie dog 
or its habitat. We recognize that city, county, and Tribal ordinances 
that address issues such as agricultural lands, transportation, and 
zoning for various types of land use have the potential to influence 
the Gunnison's prairie dog or its habitat; for example, zoning that 
protects open space might retain suitable habitat, and zoning that 
allows a housing development might destroy or fragment habitat.
    Colorado State Statute C.R.S. 30-28-101 exempts parcels of land of 
35 ac (14 ha) or more per home from regulation, so county zoning laws 
in Colorado only restrict developments with housing densities greater 
than one house per 35 ac (14 ha). This State statute allows some 
parcels to be exempt from county regulation and may negatively impact 
some prairie dogs.

Tribal Laws and Regulations

    Approximately 49 percent of potential Gunnison's prairie dog 
habitat occurs on Tribal lands (Seglund et al. 2005, p. 21). On the 
Navajo Nation, Gunnison's prairie dog is classified as small game, and 
a hunting license is required to shoot them (Cole 2007, p. 4). In 
general, access and permission to hunt on Tribal lands are limited for 
non-Tribal members as a result of various trespass laws, but access by 
Tribal members is not limited. We are aware of no seasonal shooting 
closures in effect on Tribal land. Work on the Navajo Nation Gunnison's 
Prairie Dog Management Plan, which will incorporate elements of the 
Arizona, New Mexico, and Utah State plans, is expected to begin 
immediately after finalization of the Gunnison's prairie dog rangewide 
inventory (Cole 2007, p. 5). The Navajo Nation allows lethal and non-
lethal removal of Gunnison's prairie dogs for agricultural, human 
health, and safety purposes (Cole 2007, pp. 4, 5)
    We are not aware of any other Tribal ordinances that provide for 
protection or conservation of the Gunnison prairie dog or its habitat. 
We recognize that Tribal ordinances that address issues such as 
agricultural lands, transportation, and zoning for various types of 
land uses have the potential to influence the Gunnison's prairie dog or 
its habitat; for example, zoning that protects open space might retain 
suitable habitat, and zoning that allows a housing development might 
destroy or fragment habitat.

State Laws and Regulations

    Approximately 12 percent of Gunnison's prairie dog potential 
habitat occurs on State and Federal lands (Seglund et al. 2005, pp. 
82). Gunnison's prairie dogs are considered a Species of Greatest 
Conservation Need in Arizona, a State Sensitive Species in Utah, and 
have no special conservation status in Colorado or New Mexico. All four 
States discuss the Gunnison's prairie dog in Comprehensive Wildlife 
Conservation Strategies (Seglund et al. 2005, p. 55) that confer no 
regulatory mechanisms, but assert that the species is at risk, 
declining, and deserving of special management consideration.
    In Arizona, all prairie dog species are classified as nongame 
mammals, and a hunting license is required to shoot them (Underwood 
2007, p. 27). In 2001, the hunting season for Gunnison's prairie dogs 
was changed from year-round to an April 1 to June 15 closure that 
applies to Federal, State, and private lands (Underwood 2007, p. 28).
    In Colorado, the Gunnison's prairie dog is classified as a small 
game species, and take is allowed by rifle, handgun, shotgun, handheld 
bow, crossbow, pellet gun, slingshot, falconry, and toxicants (CDOW 
2007, pp. 41-42). A small game license is required, with the exception 
of private landowners and their immediate family members or designees, 
who may take Gunnison's prairie dogs causing damage on their lands. 
Shooting on public lands is not allowed between March 1 and June 14 (no 
take is permitted in any season on national wildlife refuges) (CDOW 
2007, pp. 41-42). During the open season, no bag or possession limits 
exist; however, contestants in shooting events may take no more than 
five prairie dogs per event (CDOW 2007, pp. 41-42). No seasonal 
shooting closures are in effect on private or Tribal lands.
    In New Mexico, Gunnison's prairie dogs may be taken year-round 
without a permit by residents; non-residents are required to obtain a 
New Mexico hunting license to shoot prairie dogs within the State 
(Seglund et al. 2005, pp. 31, 32).
    In Utah, shooting of Gunnison's prairie dogs is prohibited on 
public lands from April 1 to June 15, but they may be taken on private 
lands year-round; no license is required for shooting Gunnison's 
prairie dogs, and no bag limit exists (Lupis et al. 2007, pp. 18-19).
    Access and permission to hunt on private and Tribal lands are 
limited as a result of various trespass laws. All States that provide 
habitat for Gunnison's prairie dogs allow their removal for 
agricultural, human health, and safety purposes (Seglund et al. 2005, 
p. 46).
    The States within the range of the Gunnison's prairie dog developed 
a Rangewide Conservation Strategy that provides guidance regarding 
specific activities to include in individual State plans for prairie 
dog conservation and

[[Page 6673]]

management (Seglund et al. 2005, p. 55). All of the States with 
Gunnison's prairie dog habitat are in the process of developing State 
Conservation Plans. The four plans are in different phases of 
development but are scheduled for completion by March 2008. The four 
States have agreed on a monitoring strategy to determine population 
trends of Gunnison's prairie dog across their range (Van Pelt 2007, p. 
2).
    Within Colorado, in the montane portion of the species' range, CDOW 
has designated individual population areas to identify where Gunnison's 
prairie dogs exist and where management activities should be focused. 
This portion of the species' range is comprised of the Gunnison, San 
Luis Valley, South Park, and Southeast population areas.
    The Gunnison population area is approximately 68 percent Federal, 
and 2 percent State, 30 percent private ownership (CDOW 2007, p. 2). 
The San Luis Valley population area is approximately 40 percent 
Federal, 6 percent State, and 54 percent private ownership (CDOW 2007, 
p. 2). The South Park and Southeast population areas are 34 percent 
Federal, 7 percent State, and 59 percent private ownership. The large 
percentage of private lands, where minimal regulatory mechanisms exist, 
appears to compound the effects of shooting and poisoning in this 
montane portion of the species' range that is already at lower 
occupancy than the prairie portion of the species, especially in 
conjunction with plague for which there are no regulatory or protective 
mechanisms.

United States Federal Laws and Regulations

    Federal agencies are responsible for managing approximately 17 
percent of Gunnison's prairie dog habitat. The primary Federal agency 
managing Gunnison's prairie dog habitat is BLM (12 percent); the USFS 
(4.3 percent), National Park Service (0.5 percent), Department of 
Defense (0.4 percent), and the Service (0.1 percent) also contribute to 
management of the species.

Bureau of Land Management

    The Federal Land Policy and Management Act of 1976 (FLPMA) (43 
U.S.C. 1701 et seq.) is the primary Federal law governing most land 
uses on BLM lands. Section 102(a)(8) of FLPMA specifically recognizes 
wildlife and fish resources as being among the uses for which these 
lands are to be managed. BLM must consider the needs of wildlife, 
including general considerations of Gunnison's prairie dogs, when 
conducting activities in their habitat.
    The Gunnison's prairie dog is designated by BLM as a sensitive 
species in Utah only; therefore, they are not required to provide 
special protections and mitigation during project and activity planning 
in Arizona, Colorado, or New Mexico.
    BLM's Resource Management Plans (RMPs) are the basis for all of its 
actions and authorizations involving BLM-administered lands and 
resources. They establish allowable resource uses; resource condition, 
goals and objectives to be attained; program constraints and general 
management practices needed to attain the goals and objectives; general 
implementation sequences; and intervals and standards for monitoring 
and evaluating the plan to determine its effectiveness and the need for 
amendment or revision (43 CFR 1601.0-5(k)).
    RMPs provide a framework and programmatic guidance for site-
specific activity plans. Site-specific plans address livestock grazing, 
oil and gas field development, travel management, wildlife habitat 
management, and other activities. Activity plan decisions normally 
require National Environmental Policy Act (NEPA) (42 U.S.C. 4321 et 
seq.) analysis.
    The BLM has regulatory authority for oil and gas leasing and 
operating, as provided at 43 CFR 3100 et seq. BLM usually incorporates 
stipulations as a condition of issuing a lease. The BLM's planning 
handbook has program-specific guidance for fluid minerals (which 
include oil and gas) that specifies that RMP decision-makers will 
consider restrictions on areas subject to leasing, including closures, 
and lease stipulations (BLM 2000, Appendix C, p. 6). The handbook also 
specifies that all stipulations must have waiver, exception, or 
modification criteria documented in the plan, and indicates that the 
least restrictive constraint to meet the resource protection objective 
should be used (BLM 2000, Appendix C, p. 6). The BLM has regulatory 
authority to condition drilling permits to include prairie dog 
conservation stipulations (BLM 2004, pp. 3-60). Some oil and gas leases 
have a 0.12-mi (0.19-km) stipulation, which allows movement of the 
drilling area by that distance (BLM 2004). We do not have data to 
evaluate the effectiveness of BLM's program on prairie dog 
conservation.

U.S. Forest Service

    The Gunnison prairie dog is a USFS Sensitive Species in New Mexico 
and Colorado, where it is considered to be imperiled (USFS 2007, line 
135) based on NatureServe rankings (USFS 2004, pp. 60, 64). Management 
of Federal activities on National Forest System lands is guided 
principally by the National Forest Management Act (NFMA) (16 U.S.C. 
1600-1614, August 17, 1974, as amended). The NFMA specifies that all 
national forests and grasslands must have a Land and Resource 
Management Plan (LRMP) (16 U.S.C. 1600) to guide and set standards for 
natural resource management activities. The NFMA requires the USFS to 
incorporate standards and guidelines into LRMPs (16 U.S.C. 1600). This 
has historically been done through a NEPA process. Provisions to manage 
plant and animal communities for diversity, based on the suitability 
and capability of a specific land area, are developed in order to meet 
overall multiple-use objectives.
    The 1982 NFMA implementing regulation for land and resource 
management planning (1982 rule, 36 CFR 219), under which all existing 
forest plans were prepared, requires the USFS to manage habitat to 
maintain viable populations of existing native vertebrate species on 
National Forest System lands (1982 rule, 36 CFR 219.19). A new USFS 
planning regulation was promulgated on January 5, 2005 (70 FR 1023), 
and supersedes the 1982 rule. Plans developed under the new regulation 
are to be more strategic and less prescriptive in nature than those 
developed under the 1982 planning rule. For example, previous plans 
might have included a buffer for activities near the nest sites of 
birds sensitive to disturbance. Under the new regulation, a desired 
condition description and guidelines will be provided, rather than a 
set of prescriptive standards that apply to projects. Planning, and 
decisions for projects and activities, will address site-specific 
conditions and identify appropriate conservation measures to take for 
each project or activity. However, this planning regulation was struck 
down by the U.S. District Court for the Northern District of California 
on March 30, 2007, and is not currently in use by the USFS. We are 
uncertain which direction the USFS is implementing for the Gunnison's 
prairie dog, or whether Gunnison's prairie dog habitat objectives and 
conservation measures have been incorporated into grazing allotment 
plans or LRMPs.

Summary of Factor D

    On a basis on a review of the available existing information, it 
does not appear that the inadequacy of existing regulatory mechanisms 
is a significant threat to the Gunnison's prairie dog.

[[Page 6674]]

However, the percentage of private lands within the montane portion of 
the species' range results in a paucity of regulatory mechanisms that 
potentially result in increased shooting and poisoning, which 
exacerbate the effects of plague in that portion of its range. At this 
time, no regulatory mechanisms exist to mitigate the effects of plague.

E. Other Natural or Manmade Factors

    Poisoning of Gunnison's prairie dogs has historically been 
documented throughout the species' range, but no evidence indicates 
that poisoning currently occurs on a broad scale. The WAFWA Gunnison's 
Prairie Dog Conservation Assessment summarizes poisoning campaigns in 
the four States (Seglund et al. 2005, pp. 56-57). From 1914 to 1964, 
2,310,203 ac (934,906 ha) of Gunnison's prairie dog habitat were 
poisoned in Arizona; 23,178,959 ac (9,380,192 ha) of habitat were 
poisoned in Colorado; 20,501,301 ac (8,296,582 ha) of habitat were 
poisoned in New Mexico; and 2,715,930 ac (1,099,098 ha) of habitat were 
poisoned in Utah. On public lands, poisoning efforts have led to a 
reduction in occupied habitat, extirpation from local areas, 
fragmentation, and isolation of colonies. Poisoning in all States 
became less common after Federal regulation of pesticides was enacted. 
State and Federal agencies are rarely involved in control efforts 
unless human health and safety are at risk (Seglund et al. 2005, p. 
57). Individual landowners may still control prairie dogs on their 
private property.
    No studies indicate that drought has a negative rangewide effect on 
Gunnison's prairie dogs. Impacts to the Gunnison's prairie dog under 
predicted future climate change are unclear. A trend of warming in the 
mountains of western North America is expected to decrease snowpack, 
hasten spring runoff, and reduce summer flows (IPCC 2007, p. 10). 
Increased summer heat may increase the frequency and intensity of 
wildfires (IPCC 2007, p. 14). Given the different climate variables 
between the montane and prairie geographic areas, populations in 
prairie habitat may show evidence of effects from climate change 
earlier than those in montane habitat. While it appears reasonable to 
assume that Gunnison's prairie dogs may be affected, we lack sufficient 
certainty on knowing how climate change will affect the species, or the 
potential changes to the level of threat posed by plague. The most 
recent literature on climate change includes predictions of hydrologic 
changes, higher temperatures, and expansion of drought areas, resulting 
in an upward shift in range for many species (IPCC 2007, pp. 2-5); the 
higher elevation montane habitat could be essential to future 
conservation of the Gunnison's prairie dog. We have no knowledge of 
more detailed climate change information specifically for this montane 
portion of the Gunnison's prairie dog range.

Summary of Factor E

    Although poisoning contributed historically to large declines in 
occupied area of Gunnison's prairie dogs, there is no information 
available to indicate that poisoning occurs at more than a localized 
scale today. Poisoning could have a negative effect on small, isolated 
populations, particularly in conjunction with disease and shooting; 
therefore, poisoning in the montane area may be more likely to 
contribute to the decline of the species by further fragmenting the 
small populations and curtailing recolonization. No information 
currently indicates that drought negatively affects or is likely to 
affect the Gunnison's prairie dog throughout its range, or that climate 
change will affect the species within the foreseeable future. While 
poisoning of Gunnison's prairie dogs and the effects of climate change 
in the montane portion of the range are issues important to monitor, we 
conclude that no other natural or manmade factors are a significant 
threat to this species, at this time, throughout all or a significant 
portion of its range.

Foreseeable Future

    When determining whether a species is in danger of extinction 
throughout all or a significant portion of its range, or is likely to 
become in danger of extinction in the foreseeable future, we must 
define that foreseeable future for the species. We do this on a case-
by-case basis, taking into account a variety of species-specific 
factors such as lifespan, genetics, breeding behavior, demography, 
threat-projection timeframes, and environmental variability. For the 
purposes of this finding, we define foreseeable future based on a 
threat-projection timeframe, because plague is likely to be the single 
greatest factor contributing to the species' future conservation 
status, as explained below.
    Life history characteristics are of secondary relevance to 
Gunnison's prairie dog foreseeable future. Gunnison's prairie dogs 
breed once per year and produce an average litter size of 3.77. They 
can become sexually mature at 1 year of age, but survivorship is less 
than 60 percent during their first year (Seglund et al. 2005, p. 15). 
These characteristics are relevant to the species' ability to sustain 
stable populations in the presence of ongoing, low intensity threats 
such as predation, poisoning, and shooting. However, we find that the 
ability of populations to recover from plague epizootics is more 
relevant to the foreseeable future of the species.
    As described under Factor C above, prairie dog populations can 
experience mortality rates of greater than 99 percent during plague 
epizootics and can be eradicated within one season due to plague. 
Recovery rates, which are key to population survival, depend on several 
factors, including susceptibility to plague, frequency of plague 
outbreaks, habitat quality, and distance to other colonies available 
for recolonization. Current data frame our analysis and help us 
understand what factors can reasonably be anticipated to meaningfully 
affect the species' future conservation status. We have documented that 
Gunnison's prairie dog occupancy varies significantly across its range, 
that susceptibility to extirpation by plague is greater in the montane 
portion of the species' range, and that metapopulation structure does 
not exist and recolonization is nearly nonexistent in the montane 
portion of the range. While we have data indicating that Gunnison's 
prairie dog numbers and populations have decreased, we currently have 
no data on which to base rates of decline in any portion of that range, 
which hinders our ability to determine the foreseeable future for the 
species. We must estimate the foreseeable future of the Gunnison's 
prairie dog based on current occupancy and our knowledge of the 
magnitude of the threat of plague. Plague has been shown to nearly 
extirpate entire population areas over a span of 3 to 10 years (such as 
South Park and San Luis Valley in Colorado and Moreno Valley in New 
Mexico) (Fitzgerald 1993; CDOW 2007; Cully et al. 1997) and can 
extirpate small populations in 1 to 2 years (Fitzgerald 1970; 
Lechleitner et al. 1962; Turner 2001).
    Plague has been present within the range of the Gunnison's prairie 
dog for 70 years (Eskey and Haas 1940, p. 6) and will likely continue 
to exist within the range in perpetuity, because it remains widespread 
and strongly entrenched among wild rodent populations in the western 
United States (Barnes 1993, p. 31). Current information suggests that 
Gunnison's prairie dog has not developed sufficient immunity to reduce 
the effects of plague; we anticipate it will not develop such immunity 
within the foreseeable future. Few records document Gunnison's

[[Page 6675]]

prairie dog individuals with plague antibody titers (Cully et al. 1997, 
p. 717; Cully and Williams 2001, p. 898). Individual prairie dogs in 
the Aubrey Valley of Arizona had antigens that provided an immune 
response similar to that expected if they had been vaccinated; however, 
the mechanism is unknown--that is, we do not know whether the response 
is a result of exposure to plague or is innate (Wagner and Van Andel 
2007, p. 2), and we do not know if the number of individual prairie 
dogs that have antigens are enough to protect whole colonies. We have 
no documented records of resistance being passed to offspring. More 
studies and testing need to be conducted on a plague vaccine that has 
had limited success in laboratory experiments on black-tailed prairie 
dogs; individual black-tailed prairie dogs have developed antigens to 
plague in response to the vaccine. The vaccine has not yet been tested 
on Gunnison's prairie dogs, and even if we had an effective vaccine, we 
currently have no method of applying it to prairie dog populations.
    We do not have sufficient information, such as trend data, on the 
trajectory of plague to develop a precise definition of foreseeable 
future. In the 70 years plague has been present in Gunnison's prairie 
dog habitat: (1) Populations in the montane portion of the range have 
become isolated and no longer comprise a metapopulation structure; and 
(2) populations in the prairie portion of the range have maintained a 
metapopulation structure, but occupancy has been reduced by 50 percent 
or more. The trajectory of plague effects is difficult to assess, 
because, as populations are reduced in size or extirpated, the effects 
of plague multiply at a faster rate. Using the best available 
information, we find that, if occupied habitat within the prairie 
portion of the range was reduced by at least 50 percent in 70 years, 
the species could be facing significant effects within a much shorter 
timeframe than another 70 years. Our best estimate at this time is that 
within half that time, another 35 years or fewer, plague may eliminate 
the metapopulation structure remaining within the prairie portion of 
the range. Therefore, we find that the foreseeable future of the 
Gunnison's prairie dog is 35 years. It is possible that Gunnison's 
prairie dogs may develop immunity to plague, or to rebound in numbers 
that enable it to withstand cyclic outbreaks of the disease, making the 
trajectory of plague longer than 35 years. It is also possible that 
plague will continue on a more rapid trajectory that extirpates 
populations at a rate we can't anticipate. However, we find that an 
estimate of 35 years as the foreseeable future of the Gunnison's 
prairie dog is reasonable, because it focuses this status review on the 
known effects from plague, and our best assessment that prairie dogs 
will not soon develop immunity to the disease. We know of no other 
species that have developed an immunity to plague.
    Based on currently available data on the continued presence of 
plague and its effects, we have determined that the species, rangewide, 
is not likely to become endangered within the foreseeable future, which 
we have determined to be the year 2043. However, while some populations 
in the montane portion of the range have so far persisted, their long-
term viability is compromised by the lack of metapopulation structure. 
In the prairie portion of the range, the many more populations and the 
metapopulation structure that enable recolonization after plague 
epizootics, continue to persist, and in our judgment, will continue to 
persist into the foreseeable future.

Significant Portion of the Range Analysis

    As required by the Act, we considered the five potential threat 
factors to assess whether the Gunnison's prairie dog is threatened or 
endangered throughout all or a significant portion of its range. When 
considering the listing status of the species, the first step in the 
analysis is to determine whether the species is in danger of extinction 
throughout all of its range. If this is the case, then we list the 
species in its entirety. For instance, if the threats to a species are 
directly acting on only a portion of its range, but they are at such a 
large scale that they place the entire species in danger of extinction, 
we would list the entire species.
    We next consider whether any significant portion of the Gunnison's 
prairie dog range meets the definition of endangered or is likely to 
become endangered in the foreseeable future (threatened). On March 16, 
2007, a formal opinion was issued by the Solicitor of the Department of 
the Interior, ``The Meaning of `In Danger of Extinction Throughout All 
or a Significant Portion of Its Range' '' (DOI 2007). A portion of a 
species' range is significant if it is part of the current range of the 
species and is important to the conservation of the species because it 
contributes meaningfully to the representation, resiliency, or 
redundancy of the species. The contribution must be at a level such 
that its loss would result in a decrease in the ability of the species 
to persist.
    The first step in determining whether a species is threatened or 
endangered in a significant portion of its range is to identify any 
portions of the range of the species that warrant further 
consideration. The range of a species can theoretically be divided into 
portions in an infinite number of ways. To identify portions that 
warrant further consideration, we determine whether there is 
substantial information indicating that (1) the portions may be 
significant, and (2) the species may be in danger of extinction there 
or likely to become so within the foreseeable future. In practice, a 
key part of this analysis is whether the threats are geographically 
concentrated in some way. If the threats to the species are essentially 
uniform throughout its range, no portion is likely to warrant further 
consideration. Moreover, if any concentration of threats applies only 
to portions of the range that are unimportant to the conservation of 
the species, such portions will not warrant further consideration.
    If we identify any portions that warrant further consideration, we 
then determine whether the species is threatened or endangered in any 
significant portion. If we determine that a portion of the range is not 
significant, we do not determine whether the species is threatened or 
endangered there.
    The terms ``resiliency,'' ``redundancy,'' and ``representation'' 
are intended to be indicators of the conservation value of portions of 
the range. Resiliency of a species allows it to recover from periodic 
disturbances. A species will likely be more resilient if large 
populations exist in high-quality habitat that is distributed 
throughout its range in a way that captures the environmental 
variability available. A portion of the range of a species may make a 
meaningful contribution to the resiliency of the species if the area is 
relatively large and contains particularly high-quality habitat, or if 
its location or characteristics make it less susceptible to certain 
threats than other portions of the range. When evaluating whether or 
how a portion of the range contributes to resiliency of the species, we 
evaluate the historical value of the portion and how frequently the 
portion is used by the species, if possible. The range portion may 
contribute to resiliency for other reasons; for instance, it may 
contain an important concentration of certain types of habitat that are 
necessary for the species to carry out its life-history functions, such 
as breeding,

[[Page 6676]]

feeding, migration, dispersal, or wintering.
    Redundancy of populations may be needed to provide a margin of 
safety for the species to withstand catastrophic events. This concept 
does not mean that any portion that provides redundancy is per se a 
significant portion of the range of a species. The idea is to conserve 
enough areas of the range so that random perturbations in the system 
only act on a few populations. Therefore, we examine each area based on 
whether that area provides an increment of redundancy that is important 
to the conservation of the species.
    Adequate representation ensures that the species' adaptive 
capabilities are conserved. Specifically, we evaluate a range portion 
to see how it contributes to the genetic diversity of the species. The 
loss of genetically based diversity may substantially reduce the 
ability of the species to respond and adapt to future environmental 
changes. A peripheral population may contribute meaningfully to 
representation if there is evidence that it provides genetic diversity 
due to its location on the margin of the species' habitat requirements.
    Based on the discussion above, we identified the montane portion of 
the current range of the Gunnison's prairie dog as warranting further 
consideration to determine if it is a significant portion of the range 
that is threatened or endangered. This portion of the range in central 
and south-central Colorado, and north-central New Mexico, constitutes 
approximately 40 percent of the current overall range.

Defining Portions of the Range

    In defining the portion of the current range that we considered 
further, we relied on range maps produced by mammalogists and 
geneticists that delineate the boundaries of the montane and prairie 
portions of the Gunnison's prairie dog's range. We believe the threats 
to the species are significantly different in the two range portions. 
The geography of each area differs significantly, affecting the ability 
of the prairie dog to respond to threats. Unpublished genetic analysis 
shows differences in Gunnison's prairie dogs between the two areas 
(Hafner et al. 2005, p. 2). This analysis is not yet complete enough to 
definitively indicate that two separate subspecies exist; however, 
along with subspecies delineation, the data also point to possible 
differences in Gunnison's prairie dog adaptations due to physical 
geography.
    We assessed whether we should consider smaller geographic units, 
such as population areas. Given the best scientific and commercial 
information available, we found that individual population areas did 
not meaningfully contribute to the representation, resiliency, or 
redundancy of the species.
    The scale at which we define the range of a particular species, 
that is, at a relatively coarse or fine scale, depends on the life 
history of the species, the data available, and the purpose for 
defining the range.
    As with other determinations under the Act, we define the current 
range on the basis of the best available data. The purpose of defining 
range (and hence the significant portion of the range) is to set the 
boundaries of the protections of the Act. Therefore, defining the 
boundaries too narrowly may lead to the failure to protect some 
Gunnison's prairie dogs. We have determined that it is appropriate to 
use a relatively coarse scale to capture all of the areas where the 
best available data suggests the Gunnison's prairie dog is likely to 
occur.
    The map boundaries in Figure 1 above show the Gunnison's prairie 
dog range. Discovery of currently existing Gunnison's prairie dog 
populations outside these boundaries is unlikely. The map boundaries 
show the significant montane portion, which is inclusive of all areas 
likely to support Gunnison's prairie dog populations in the montane 
habitat.

Significance of the Montane Range

    When Gunnison's prairie dog colonies are well distributed across 
their current range, which currently includes an estimated 5 percent of 
the historical range, they are less susceptible to extinction than when 
colonies are confined to only a portion of their range. The montane 
habitat within Gunnison's prairie dog range contains populations 
significant to the overall viability of the species, because they 
represent:
    <bullet> Approximately 40 percent of the species' current habitat;
    <bullet> Populations in unique, higher elevation habitat, and 
adaptations relevant to this habitat;
    <bullet> Genetic material substantially unique within the range of 
the Gunnison's prairie dog (Hafner 2004, p. 6; Hafner et al. 2005, p. 
2).
    The relatively large proportion of the entire range represented by 
the montane habitat adds a significant number of Gunnison's prairie dog 
populations widely distributed throughout distinct geographic areas. 
Losses of populations in montane habitat would affect the 
representation, resiliency, and redundancy of the species by increasing 
risk of extirpation by a natural or anthropogenic event, reducing 
adaptive characteristics to geographical or climatic conditions, and 
reducing remaining genetic variation.
    The most recent literature on climate change includes predictions 
of hydrologic changes, higher temperatures, and expansion of drought 
areas, resulting in an upward shift in range for many species (IPCC 
2007, pp. 2-5); the higher elevation montane habitat could be essential 
to future conservation of the Gunnison's prairie dog. These factors 
lead us to the conclusion that loss of the Gunnison's prairie dog 
within the montane portion of its range would reduce the ability of the 
species to persist.

Status of Montane Range

    If we identify any range portions as significant, we then determine 
whether the species is threatened or endangered in this significant 
portion of its range.

Summary of Factors Affecting the Species Within the Montane Portion of 
the Range

    We evaluated whether threats to the Gunnison's prairie dog may 
affect its survival within the montane portion of its range, separately 
from the entire range. Our evaluation of threats within the montane 
portion of the range (based on information provided in the petition, 
available in our files, and available in published and unpublished 
studies and reports) is presented below.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

    Conservation principles indicate that smaller, more isolated 
populations are more vulnerable to extirpation (Barnes 1993, p. 34; 
Cully 1993, p. 43; Fitzgerald 1970, p. 78; Gilpin and Soule 1986, pp. 
30-31; Miller et al. 1994, p. 151; Mulhern and Knowles 1995, p. 21; 
Wilcox and Murphy 1985, p. 883; Wuerthner 1997, p. 464). Lomolino et 
al. (2003, p. 116) found that persistence of Gunnison's prairie dog 
colonies increased significantly with larger colony size and decreased 
isolation. The populations within the montane portion of the range are 
smaller and more isolated. However, we found no studies or data that 
specifically assess the magnitude of the threats related to agriculture 
land conversions, urbanization, grazing, roads, and oil and gas 
leasing, and resulting fragmentation within the montane portion of 
Gunnison's prairie dog habitat.
    After assessing the best available science on the magnitude and 
extent of

[[Page 6677]]

the effects of agricultural land conversion, urbanization, grazing, 
roads, oil and gas development, and fragmentation of habitat, we find 
that the destruction, modification, and curtailment of Gunnison's 
prairie dog's habitat or range are not significant threats within the 
montane portion of the range. Agriculture, urbanization, roads, and oil 
and gas development each currently affect a small percentage of 
Gunnison's prairie dog habitat. Effects of livestock grazing, while 
widespread, have not resulted in measurable population declines.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    We have determined that shooting continues to be a threat to the 
Gunnison's prairie dog within the montane portion of its range and 
contributes to the decline of the species when combined with the 
effects of disease (see Factor C below). However, this threat is being 
monitored and managed by the States of Colorado and New Mexico, and 
modeling results suggest seasonal shooting closures implemented in 
Colorado will likely reduce population-level losses. Therefore, we have 
determined that overutilization for commercial, recreational, 
scientific, or educational purposes is not a significant threat to the 
Gunnison's prairie dog within the montane portion of its range.

C. Disease or Predation

    Several well-studied colonies within the montane portion of the 
Gunnison's prairie dog range have been documented as being extirpated, 
or nearly so, due to plague. The South Park, Colorado, population area 
included estimated occupied habitat of 915,000 ac (371,000 ha) in 1945; 
74,000 ac (30,000 ha) in 1948; and 42 ac (17 ha) in 2002 (CDOW 2007). 
This decline was largely due to plague and affected a substantial 
portion of the species' extant occupied habitat in Colorado (at least 
15 percent). Plague resulted in the complete loss, over a 2-year 
period, of a colony within the South Park population area (Fitzgerald 
1970, pp. 68-69). A plague event in Saguache County, Colorado, that 
progressed across seven colonies in 2 years left only scattered 
individuals surviving in two colonies (Lechleitner et al. 1968, p. 
734). In Gunnison, Saguache, and Montrose Counties, Colorado, plague 
also was responsible for a decline from 15,569 ac (6,228 ha) of 
occupied habitat in 1980, to 770 ac (308 ha) in 2002 (note that 
Montrose County is in the Southwest population area in prairie habitat) 
(Capodice and Harrell 2003, pp. 5-7). A complete die-off of a colony 
due to plague in Chubbs Park, Chaffee County, Colorado, occurred in 
1959 (Lechleitner et al. 1962, p. 185). In August 1958, the population 
was stable and healthy, but in 1959 an epizootic spread 2 mi (3 km) 
within 3 months; prairie dogs continued to be absent from the area in 
1960 and 1961, and we have no recent information on the existence of 
prairie dogs in that location.
    Approximately 1,000 to 1,500 Gunnison's prairie dogs were killed by 
an outbreak of plague in a 148-ac (60-ha) colony in Curecanti National 
Recreation Area near Gunnison, Colorado, in 1981 (Rayor 1985, p. 194). 
A few animals survived the disease and Gunnison's prairie dogs were 
again abundant in the area in 1986 (Cully 1989, p. 49). In 2002, 252 ac 
(102 ha) of habitat in the Recreation Area were occupied by Gunnison's 
prairie dog colonies (Capodice and Harrell 2003, p. 23), but the 
current estimate is 12 ac (4.8 ha) (Childers 2007, p. 2). Colonies 
within the Recreation Area experienced six plague epidemics between 
1971 and 2007. Of the 9 historic Gunnison's prairie dog colonies, 3 are 
currently active, and 2 act as source populations for the main prairie 
dog concentration area (Childers 2007, p. 1). If the source colonies 
die off due to plague, repopulation may not be possible because any 
other Gunnison's prairie dog populations remaining will be separated by 
distance (more than 6 mi (10 km)) and impassable geographical features 
such as rivers and mountains (Lomolino et al. 2003, p. 116).
    Recently, plague has been implicated in the loss of several large 
colonies on BLM land within the Gunnison, Colorado, population area 
(CDOW 2007, p. 4). A large colony southeast of Gunnison that was very 
active in 2005 was totally devoid of prairie dogs in 2006 and 2007. 
Four other large colonies in the same vicinity were active in 2006, but 
by 2007, no prairie dog activity was observed. Plague is the suspected 
cause of these extirpations because of the complete elimination of the 
prairie dogs with no sign of poisoning (CDOW 2007, p. 4).
    Fitzgerald (1993, p. 52) expressed concern about the status of the 
Gunnison's prairie dog in Colorado, indicating that plague had 
eliminated many populations, including almost all of the populations in 
South Park. He also suggested that populations appeared to be in poor 
condition in the San Luis Valley and were extirpated from the extreme 
upper Arkansas River Valley, as well as Jefferson, Douglas, and Lake 
Counties. These areas comprise most of the Gunnison's prairie dog 
montane habitat in Colorado.
    From 1984 through 1987, a plague event reduced the population of 
Gunnison's prairie dogs in the Moreno Valley of New Mexico from more 
than 100,000 individuals to between 250 and 500, a decline of greater 
than 99 percent (Cully et al. 1997, pp. 708-711). Although the 
remaining population rebounded (increased in size to a certain extent) 
following the epizootic, another plague event swept through the area in 
1988, and the population in July 1996 was still only a small fraction 
of what it had been in 1984 (Cully et al. 1997, p. 717).
    Occupancy modeling performed for Colorado in 2005 indicated a lower 
proportion of occupancy in the montane portion of the species' range 
within Colorado (3.2 percent) than in the prairie portion within 
Colorado (16.0 percent) (Andelt et al. 2006, p. 17; CDOW 2007, p. 19). 
When the study was repeated over the same plots in 2007, occupancy was 
again found to be lower (3.6 percent) in the montane range portion in 
Colorado than in the southwestern portion (18.3 percent) (CDOW 2007, p. 
19). The only recent threat responsible for whole population declines 
and extirpations, as documented in the studies cited in this section, 
is plague.
    The frequency of plague epizootics appears to be high in montane 
habitat due to moister environmental conditions that are conducive to 
greater flea densities. The impact of plague epizootics in montane 
habitat is great because the small, isolated populations cannot 
recolonize. Within the South Park, Gunnison, and Southeast montane 
population areas in Colorado, no prairie dog complexes of appreciable 
size exist, and only a few small complexes exist within the San Luis 
Valley population area (CDOW 2007, pp. 1-17). Without a metapopulation 
structure, an overall decline in persistence takes place (Lomolino and 
Smith 2001, p. 942).
    The landscape status in the montane portion of Gunnison's prairie 
dog range is characterized by fewer, smaller colonies that are 
isolated, and few to no complexes or metapopulation structure. These 
factors make the prairie dogs in this habitat highly susceptible to 
plague-related declines, and we have no evidence of recovery from 
plague in the montane habitat area.
    The studies cited above document the serious impact that plague has 
on Gunnison's prairie dogs within the montane portion of the range. 
Although plague antibody titers have been found in a few individuals, 
periodic epizootic plague events generally kill more than

[[Page 6678]]

99 percent of an affected population. Whether individual populations 
recover from these epizootics depends on two main factors: (1) The 
availability of other source populations to recolonize an area; and (2) 
the frequency of epizootic outbreaks, which can reduce population 
numbers more quickly than individual prairie dogs from neighboring 
colonies can recolonize.
    Populations in the more mesic montane areas of Gunnison's prairie 
dog range appear to have been widely and severely affected by plague. 
This may be partly due to climatic conditions, such as higher levels of 
spring moisture, which has been shown to increase flea numbers, and in 
turn, plague outbreaks. Isolation of prairie dog populations does not 
seem to protect them from the spread of plague, because it appears that 
plague exists with all parts of the range at some level and can be 
spread by wider-ranging animals. The case studies cited in this section 
indicate that large populations have been repeatedly affected by plague 
and have shown no substantial recovery over long periods of time--
decades in some cases. This has left smaller, more scattered 
populations throughout the montane range portion, with the result that 
areas affected by plague are less likely to be recolonized by nearby 
populations. While little information is currently available on prairie 
dog movement within this montane habitat, its geography (populations 
are located in valleys between mountainous areas) probably impedes the 
ability of prairie dogs to recolonize populations. Within this 
geographic area, CDOW found slightly more than 3 percent occupancy of 
surveyed plots (CDOW 2007, p.19).
    Populations within montane habitat have three distinct 
disadvantages in resisting the effects of plague:
    (1) A higher frequency of epizootics due to the moister montane 
climate that is conducive to higher abundance of fleas that spread 
plague;
    (2) smaller populations that cannot recover in numbers from plague 
epizootics; and
    (3) isolated populations and no metapopulation structure, due to 
reduced population sizes from past plague epizootics and montane 
geography, and therefore a significantly limited ability to recolonize.
    After assessing the best available science on the magnitude and 
extent of the effects of plague, we find that plague is significantly 
impacting the species in the montane portion of its range.

D. Inadequacy of Existing Regulatory Mechanisms

    On the basis on a review of the available existing information, it 
does not appear that the inadequacy of existing regulatory mechanisms 
is a significant threat to the Gunnison's prairie dog. However, the 
percentage of private lands within the montane portion of the species' 
range results in a paucity of regulatory mechanisms that potentially 
result in increased shooting and poisoning, which exacerbate the 
effects of plague in that portion of its range. At this time, no 
regulatory mechanisms exist to mitigate the effects of plague.

E. Other Natural or Manmade Factors

    Poisoning could have a negative effect on small, isolated 
populations, particularly in conjunction with disease and shooting; 
therefore, poisoning in the montane area may be more likely to 
contribute to the decline of the species by further fragmenting the 
small populations and curtailing recolonization. However, while 
poisoning bears monitoring, at this time, we conclude that it is not 
significantly affecting the populations within this portion of the 
range. No information currently indicates that drought negatively 
affects, or is likely to affect, the Gunnison's prairie dog within the 
montane portion of its range, or that climate change will affect the 
species within the foreseeable future; however, various scenarios are 
plausible. We conclude that no other natural or manmade factors are a 
significant threat to this species, at this time, throughout the 
montane portion of its range.

Finding

    The information summarized in this status review includes 
substantial information that was not available at the time of the 90-
day petition finding (71 FR 6241, February 7, 2006) and other 
information we received during the public comment period following the 
publication of the 90-day finding. This 12-month finding reflects and 
incorporates information we received during the public comment period 
or obtained through consultation, literature research, and field 
visits, and responds to significant issues identified. We determined 
that the Gunnison's prairie dog does not meet the definition of 
threatened or endangered throughout its entire range, because, within 
approximately 60 percent of its range (the prairie habitat in the 
southwestern portion of its range), the threats (primarily plague) are 
not of a magnitude that currently puts the species in danger of 
extinction (endangered), or makes it likely to become endangered within 
the foreseeable future (threatened). However, we determined that the 
Gunnison's prairie dog is warranted for listing within the montane 
portion of its range (approximately 40 percent of the species total 
range).
    The determination of a finding of threatened or endangered involves 
weighing the magnitude and immediacy of the threats. The cumulative 
magnitude of threats within the montane portion of the range is high. 
Immediacy of threats varies geographically across the montane range, 
but is high in areas of the montane habitat where populations have 
already been extirpated, primarily the South Park and Southeast 
population areas.
    Within the prairie portion of the Gunnison's prairie dog's range, 
colonies are subject to the same threats, but at a different magnitude. 
Plague has the same potential to reduce population size significantly 
there as in montane habitat, but due to more open geography, an 
existing metapopulation structure, larger population sizes, and 
proximity of other colonies, recolonization has been observed. The 
ability of populations to recolonize relatively quickly enables them to 
recover more fully between plague enzootics. Ability to recolonize in 
prairie habitat also enables Gunnison's prairie dog populations to 
recover from poisoning and shooting, which act to exacerbate the more 
significant threat from plague. The species' status in this portion of 
the range is characterized by a metapopulation structure, and larger 
colonies and complexes that are better able to recover from plague 
epidemics, to be recolonized after plague epizootics, and even to 
colonize new areas.
    We determined that the Gunnison's prairie dog is warranted for 
listing within the montane portion of its range (approximately 40 
percent of the species total range). We find that threats, primarily 
plague, exist in the montane portion of their range at a magnitude that 
make the species likely to become threatened or endangered within the 
foreseeable future, which we have determined to be the year 2043. We 
determined that Gunnison's prairie dog populations within the prairie 
portion of the range continue to be viable due to the functioning 
metapopulation structure and the apparent resistance to plague 
epizootics within the Aubrey Valley, Arizona, complex. Therefore, we 
find that the Gunnison's prairie dog does not warrant listing 
throughout its

[[Page 6679]]

entire range, but that populations within the montane portion of its 
range are significant to the continued existence of the species and 
warrants listing in that portion only (see discussion under Significant 
Portion of the Range Analysis). However, listing the montane Gunnison's 
prairie dog is warranted but precluded at this time by pending 
proposals for other species with higher listing priorities based on 
taxonomic uniqueness (the only species described for the genus), or 
other species that are not currently listed (see discussion under 
Preclusion and Expeditious Progress).
    If future genetic analyses or taxonomic studies indicate 
conclusively that two subspecies of Gunnison's prairie dogs exist, this 
would affect our proposed listing. Instead of defining the montane 
habitat as a significant portion of the range, we would propose listing 
the subspecies that exists in that habitat.
    Sylvatic plague is the only significant factor affecting the future 
conservation status of the species. Within the montane portion of the 
species' range, the threat of plague has greater magnitude, and colony 
recovery from plague is slow or nonexistent. Distributional data 
indicate that the species' status in this portion of its range is 
characterized by lower occupancy, smaller colony sizes, and fragmented 
and isolated colonies that impede recovery and persistence of 
populations. Reliable data regarding the status of the Gunnison's 
prairie dog are predominantly in the form of percent occupancy studies, 
which indicate significantly lower occupancy in montane habitat (for 
Colorado, approximately 3.6 percent versus 18.3 percent in prairie 
habitat). For example, the South Park population area, which comprises 
nearly 15 percent of the species' habitat in Colorado, is nearly devoid 
of the species. Within the four montane population areas in Colorado, 
prairie dog complexes exist within only one, and those complexes are 
few and small. With little or no metapopulation structure, an overall 
decline in persistence is apparent in the montane habitat.
    Populations within montane habitat have three distinct 
disadvantages in resisting the effects of plague: (1) A higher 
frequency of epizootics due to the moister montane climate that is 
conducive to higher abundance of fleas that spread plague; (2) smaller 
populations that cannot recover in numbers from plague epizootics; and 
(3) isolated populations and little or no metapopulation structure, due 
to reduced population sizes from past plague epizootics and montane 
geography, and therefore a significantly limited ability to recolonize.
    Some lands within the montane range supporting the Gunnison's 
prairie dog are controlled by Federal or State agencies, or have been 
set aside as open space by local governments. However, a greater 
portion of the montane range is private land with fewer regulatory 
mechanisms in place for conserving prairie dogs.
    We found that poisoning and shooting are not significant threats 
rangewide. While they can have greater impacts on small populations by 
compounding the effects from the primary threat of plague and further 
decreasing colony size and fragmenting and isolating colonies, at this 
time poisoning and shooting do not appear to be occurring at a level 
that raises concern above that related to plague. Cumulative threats 
do, however, impede recovery of some populations and imperil others. 
Where recovery does not occur, Gunnison's prairie dog populations are 
likely to remain small, fragmented, and susceptible to extirpation.
    The following summarizes the key points leading to our finding:
    (1) Historic data indicate a decline from 24,000,000 ac (9,700,000 
ha) of occupied habitat to between 340,000 and 500,000 ac (136,000 to 
200,000 ha).
    (2) Recent data indicate that approximately 3.6 percent of 
potential Gunnison's prairie dog habitat is occupied in the montane 
portion of the range, as compared to 18.3 percent occupancy in the 
prairie portion of the range.
    (3) The Gunnison's prairie dog occupies two genetically important 
areas of its range (prairie and montane portions). The two portions 
have different geographical features and different responses to plague.
    (4) Plague has resulted in large reductions in prairie dogs and 
occupied habitat within both portions of the range. The prairie portion 
of the range is responding to plague by recolonizing affected 
populations. Within the montane portion of the range, the plague 
response is more significant (large population losses, loss of all 
metapopulation structure, nearly no recolonization occurring, and 
entire population areas nearly devoid of prairie dogs).
    (5) We determined that the Gunnison's prairie dog is warranted for 
listing in the montane portion because:
    (A) The montane portion of the range is significant to the species' 
viability (it represents approximately 40 percent of the species' 
habitat; populations are adapted to unique, montane habitat; and these 
animals are genetically unique).
    (B) Loss of Gunnison's prairie dogs in the montane portion would 
affect:
    (i) resiliency of the species, because the montane portion 
represents approximately 40 percent of the species range, and the 
small, isolated populations are not likely to rebound after decimation 
from plague;
    (ii) redundancy of the species, because random perturbations are 
not likely to act equally on both the montane and prairie portions; and
    (iii) representation of the species, because the montane population 
is genetically distinct from the prairie population and the species' 
remaining genetic diversity would be reduced.
    (C) The species is warranted for listing in this portion of the 
range because:
    (i) Occupancy data (3 percent) is significantly lower in the 
montane range portion.
    (ii) The montane portion of the range no longer has a 
metapopulation structure, and populations reduced by plague have not 
rebounded; repopulation from nearby populations has been curtailed by 
distance and geographical barriers.
    (iii) The two portions of the range are separated by mountain 
ranges that almost completely limit prairie dog movement between them.
    (iv) Populations within the montane portion of the range are 
separated from each other by four mountain ranges and several large 
rivers, which preclude repopulation after plague epizootics.
    (v) Some entire population areas within montane range are now 
nearly devoid of Gunnison's prairie dogs.
    (vi) Plague appears to be more prevalent in the montane portion of 
the range, possibly due to greater flea populations that thrive in 
moister climates.
    We determined that the magnitude of threats affecting the 
Gunnison's prairie dog in the montane portion of its range is ``high,'' 
because plague is significantly affecting the remaining small, isolated 
populations, and plague epizootics can extirpate populations there 
within a short timeframe (3 to 10 years); metapopulation structure in 
the prairie portion of the range exists, facilitating recolonization 
when populations are extirpated. We find that the threat posed by 
plague is ``imminent'' because plague epizootics are known to be 
occurring and the effects are measurable. Therefore, pursuant to our 
September 21, 1983 (48 FR 43098) Listing and Recovery Priority 
Guidelines, we assign a LPN of 2 to this portion of the species' range.
    We reviewed the available information to determine if existing and

[[Page 6680]]

foreseeable threats to the Gunnison's prairie dog within montane 
habitat are of sufficient extent and magnitude to require emergency 
listing as threatened or endangered. We have determined that an 
emergency listing is not warranted for this species at this time, 
because populations are currently not threatened in the prairie portion 
of the range, and because emergency listing would not lessen the 
effects from plague, which is the significant threat in the montane 
portion of the range.

Preclusion and Expeditious Progress

    Preclusion is a function of the listing priority of a species in 
relation to the resources that are available and competing demands for 
those resources. Thus, in any given fiscal year (FY), multiple factors 
dictate whether it will be possible to undertake work on a proposed 
listing regulation or whether promulgation of such a proposal is 
warranted but precluded by higher-priority listing actions.
    The resources available for listing actions are determined through 
the annual Congressional appropriations process. The appropriation for 
the Listing Program is available to support work involving the 
following listing actions: proposed and final listing rules; 90-day and 
12-month findings on petitions to add species to the Lists of 
Endangered and Threatened Wildlife and Plants or to change the status 
of a species from threatened to endangered; annual determinations on 
prior ``warranted but precluded'' petition findings as required under 
section 4(b)(3)(C)(i) of the Act; proposed and final rules designating 
critical habitat; and litigation-related, administrative, and program 
management functions (including preparing and allocating budgets, 
responding to Congressional and public inquiries, and conducting public 
outreach regarding listing and critical habitat). The work involved in 
preparing various listing documents can be extensive and may include, 
but is not limited to: gathering and assessing the best scientific and 
commercial data available and conducting analyses used as the basis for 
our decisions; writing and publishing documents; and obtaining, 
reviewing, and evaluating public comments and peer review comments on 
proposed rules and incorporating relevant information into final rules. 
The number of listing actions that we can undertake in a given year 
also is influenced by the complexity of those listing actions; that is, 
more complex actions generally are more costly. For example, during the 
past several years, the cost (excluding publication costs) for 
preparing a 12-month finding, without a proposed rule, has ranged from 
approximately $11,000 for one species with a restricted range and 
involving a relatively uncomplicated analysis to $305,000 for another 
species that is wide-ranging and involving a complex analysis.
    We cannot spend more than is appropriated for the Listing Program 
without violating the Anti-Deficiency Act (see 31 U.S.C. 
1341(a)(1)(A)). In addition, in FY 1998 and for each fiscal year since 
then, Congress has placed a statutory cap on funds which may be 
expended for the Listing Program, equal to the amount expressly 
appropriated for that purpose in that fiscal year. This cap was 
designed to prevent funds appropriated for other functions under the 
Act (for example, recovery funds for removing species from the Lists), 
or for other Service programs, from being used for Listing Program 
actions (see House Report 105-163, 105th Congress, 1st Session, July 1, 
1997).
    Recognizing that designation of critical habitat for species 
already listed would consume most of the overall Listing Program 
appropriation, Congress also put a critical habitat subcap in place in 
FY 2002 and has retained it each subsequent year to ensure that some 
funds are available for other work in the Listing Program: ``The 
critical habitat designation subcap will ensure that some funding is 
available to address other listing activities'' (House Report No. 107-
103, 107th Congress, 1st Session, June 19, 2001). In FY 2002 and each 
year until FY 2006, the Service has had to use virtually the entire 
critical habitat subcap to address court-mandated designations of 
critical habitat, and consequently none of the critical habitat subcap 
funds have been available for other listing activities. In FY 2007, we 
were able to use some of the critical habitat subcap funds to fund 
proposed listing determinations for high-priority candidate species; we 
expect to also be able to do this in FY 2008.
    Thus, through the listing cap, the critical habitat subcap, and the 
amount of funds needed to address court-mandated critical habitat 
designations, Congress and the courts have in effect determined the 
amount of money available for other listing activities. Therefore, the 
funds in the listing cap, other than those needed to address court-
mandated critical habitat for already listed species, set the limits on 
our determinations of preclusion and expeditious progress.
    Congress also recognized that the availability of resources was the 
key element in deciding whether, when making a 12-month petition 
finding, we would prepare and issue a listing proposal or make a 
``warranted but precluded'' finding for a given species. The Conference 
Report accompanying Public Law 97-304, which established the current 
statutory deadlines and the warranted-but-precluded finding, states (in 
a discussion on 90-day petition findings that by its own terms also 
covers 12-month findings) that the deadlines were ``not intended to 
allow the Secretary to delay commencing the rulemaking process for any 
reason other than that the existence of pending or imminent proposals 
to list species subject to a greater degree of threat would make 
allocation of resources to such a petition [that is, for a lower-
ranking species] unwise.''
    In FY 2008, expeditious progress is that amount of work that can be 
achieved with $8,206,940, which is the amount of money that Congress 
appropriated for the Listing Program at this time (that is, the portion 
of the Listing Program funding not related to critical habitat 
designations for species that are already listed). Our process is to 
make our determinations of preclusion on a nationwide basis to ensure 
that the species most in need of listing will be addressed first and 
also because we allocate our listing budget on a nationwide basis. The 
$8,206,940 for listing activities (that is, the portion of the Listing 
Program funding not related to critical habitat designations for 
species that already are listed) will be used to fund work in the 
following categories: compliance with court orders and court-approved 
settlement agreements requiring that petition findings or listing 
determinations be completed by a specific date; section 4 (of the Act) 
listing actions with absolute statutory deadlines; essential 
litigation-related, administrative, and program management functions; 
and high-priority listing actions. The allocations for each specific 
listing action are identified in the Service's FY 2008 Draft Allocation 
Table (part of our administrative record). We are working on completing 
our allocation at this time. More funds are available in FY 2008 than 
in previous years to work on listing actions that are not the subject 
of court orders or court-approved settlement agreements.
    Our decision that a proposed rule to list the montane portion of 
the Gunnison's prairie dog is warranted but precluded includes 
consideration of its listing priority. In accordance with guidance we 
published on September 21, 1983, we assign an LPN to each candidate 
species (48 FR 43098). Such a priority ranking guidance system is 
required under section 4(h)(3) of the Act

[[Page 6681]]

(16 U.S.C. 1533(h)(3)). Using this guidance, we assign each candidate 
an LPN of 1 to 12, depending on the magnitude of threats (high vs. 
moderate to low), immediacy of threats (imminent or non-imminent), and 
taxonomic status of the species, in order of priority (monotypic genus 
(a species that is the sole member of a genus), species, subspecies, 
distinct population segment, or significant portion of the range). The 
lower the listing priority number, the higher the listing priority 
(that is, a species with an LPN of 1 would have the highest listing 
priority).
    We currently have more than 120 species with an LPN of 2. 
Therefore, we further rank the candidate species with an LPN of 2 by 
using the following extinction-risk type criteria: International Union 
for the Conservation of Nature and Natural Resources (IUCN) Red list 
status/rank, Heritage rank (provided by NatureServe), Heritage threat 
rank (provided by NatureServe), and species currently with fewer than 
50 individuals, or 4 or fewer populations. Those species with the 
highest IUCN rank (critically endangered), the highest Heritage rank 
(G1), the highest Heritage threat rank (substantial, imminent threats), 
and currently with fewer than 50 individuals, or fewer than 4 
populations, comprise a list of approximately 40 candidate species 
(``Top 40''). These 40 candidate species have the highest priority to 
receive funding to work on a proposed listing determination. To be more 
efficient in our listing process, as we work on proposed rules for 
these species in the next several years, we are preparing multi-species 
proposals when appropriate, and these may include species with lower 
priority if they overlap geographically or have the same threats as a 
species with an LPN of 2. In addition, available staff resources are 
also a factor in determining high-priority species provided with 
funding. Finally, proposed rules for reclassification of threatened 
species to endangered are lower priority, since the listing of the 
species already affords the protection of the Act and implementing 
regulations. We assigned the montane portion of the Gunnison's prairie 
dog an LPN of 5, based on our finding that the species faces threats of 
high magnitude that are not imminent.
    As explained above, a determination that listing is warranted but 
precluded must also demonstrate that expeditious progress is being made 
to add or remove qualified species to and from the Lists of Endangered 
and Threatened Wildlife and Plants. (We note that we do not discuss 
specific actions taken on progress towards removing species from the 
Lists because that work is conducted using appropriations for our 
Recovery program, a separately budgeted component of the Endangered 
Species Program. As explained above in our description of the statutory 
cap on Listing Program funds, the Recovery Program funds and actions 
supported by them cannot be considered in determining expeditious 
progress made in the Listing Program.) As with our ``precluded'' 
finding, expeditious progress in adding qualified species to the Lists 
is a function of the resources available and the competing demands for 
those funds. Our expeditious progress in FY 2007 in the Listing 
Program, up to the date of making this finding for the Gunnison's 
prairie dog, included preparing and publishing the following 
determinations:

                                        FY 2007 Completed Listing Actions
----------------------------------------------------------------------------------------------------------------
     Publication date                 Title                   Actions                      FR pages
----------------------------------------------------------------------------------------------------------------
10/11/2006................  Withdrawal of the          Final withdrawal,     71 FR 59700-59711
                             Proposed Rule To List      Threats eliminated.
                             the Cow Head Tui Chub
                             (Gila biocolor
                             vaccaceps) as Endangered.
10/11/2006................  Revised 12-Month Finding   Notice of 12-month    71 FR 59711-59714
                             for the Beaver Cave        petition finding,
                             Beetle                     Not warranted.
                             (Pseudanophthalmus
                             major).
11/14/2006................  12-Month Finding on a      Notice of 12-month    71 FR 66292-66298
                             Petition To List the       petition finding,
                             Island Marble Butterfly    Not warranted.
                             (Euchloe ausonides
                             insulanus) as Threatened
                             or Endangered.
11/14/2006................  90-Day Finding for a       Notice of 90-day      71 FR 66298-66301
                             Petition To List the       petition finding,
                             Kennebec River             Substantial.
                             Population of Anadromous
                             Atlantic Salmon as Part
                             of the Endangered Gulf
                             of Maine Distinct
                             Population Segment.
11/21/2006................  90-Day Finding on a        Notice of 90-day      71 FR 67318-67325
                             Petition To List the       petition finding,
                             Columbian Sharp-Tailed     Not substantial.
                             Grouse as Threatened or
                             Endangered.
12/5/2006.................  90-Day Finding on a        Notice of 90-day      71 FR 70483-70492
                             Petition To List the       petition finding,
                             Tricolored Blackbird as    Not substantial.
                             Threatened or Endangered.
12/6/2006.................  12-Month Finding on a      Notice of 12-month    71 FR 70717-70733
                             Petition To List the       petition finding,
                             Cerulean Warbler           Not warranted.
                             (Dendroica cerulea) as
                             Threatened with Critical
                             Habitat.
12/6/2006.................  90-Day Finding on a        Notice of 90-day      71 FR 70715-70717
                             Petition To List the       petition finding,
                             Upper Tidal Potomac        Not substantial.
                             River Population of the
                             Northern Water Snake
                             (Nerodia sipedon) as an
                             Endangered Distinct
                             Population Segment.
12/14/2006................  90-Day Finding on a        Notice of 5-year      71 FR 75215-75220
                             Petition To Remove the     review, Initiation.
                             Uinta Basin Hookless      Notice of 90-day
                             Cactus From the List of    petition finding,
                             Endangered and             Not substantial.
                             Threatened Plants; 90-    Notice of 90-day
                             Day Finding on a           petition finding,
                             Petition To List the       Substantial.
                             Pariette Cactus as
                             Threatened or Endangered.
12/19/2006................  Withdrawal of Proposed     Notice of             71 FR 76023-76035
                             Rule To List Penstemon     withdrawal, More
                             grahamii (Graham's         abundant than
                             beardtongue) as            believed, or
                             Threatened With Critical   diminished threats.
                             Habitat.
12/19/2006................  90-Day Finding on          Notice of 90-day      71 FR 76057-76079
                             Petitions To List the      petition finding,
                             Mono Basin Area            Not substantial.
                             Population of the
                             Greater Sage-Grouse as
                             Threatened or Endangered.
1/9/2007..................  12-Month petition finding  Notice of 12-month    72 FR 1063-1099
                             and Proposed Rule To       petition finding,
                             List the Polar Bear        Warranted.
                             (Ursus maritimus) as      Proposed Listing,
                             Threatened Throughout      Threatened.
                             Its Range; Proposed Rule.

[[Page 6682]]

 
1/10/2007.................  Endangered and Threatened  Clarification of      72 FR 1186-1189
                             Wildlife and Plants;       findings.
                             Clarification of
                             Significant Portion of
                             the Range for the
                             Contiguous United States
                             Distinct Population
                             Segment of the Canada
                             Lynx.
1/12/2007.................  Withdrawal of Proposed     Notice of             72 FR 1621-1644
                             Rule To List Lepidium      withdrawal, More
                             papilliferum (Slickspot    abundant than
                             Peppergrass).              believed, or
                                                        diminished threats.
2/2/2007..................  12-Month Finding on a      Notice of 12-month    72 FR 4967-4997
                             Petition To List the       petition finding,
                             American Eel as            Not warranted.
                             Threatened or Endangered.
2/13/2007.................  90-Day Finding on a        Notice of 90-day      72 FR 6699-6703
                             Petition To List the       petition finding,
                             Jollyville Plateau         Substantial.
                             Salamander as Endangered.
2/13/2007.................  90-Day Finding on a        Notice of 90-day      72 FR 6703-6707
                             Petition To List the San   petition finding,
                             Felipe Gambusia as         Not substantial.
                             Threatened or Endangered.
2/14/2007.................  90-Day Finding on a        Notice of 90-day      72 FR 6998-7005
                             Petition To List           petition finding,
                             Astragalus debequaeus      Not substantial.
                             (DeBeque milkvetch) as
                             Threatened or Endangered.
2/21/2007.................  90-Day Finding on a        Notice of 5-year      72 FR 7843-7852
                             Petition To Reclassify     review, Initiation.
                             the Utah Prairie Dog      Notice of 90-day
                             From Threatened to         petition finding,
                             Endangered and             Not substantial.
                             Initiation of a 5-Year
                             Review.
3/8/2007..................  90-Day Finding on a        Notice of 90-day      72 FR 10477-10480
                             Petition To List the       petition finding,
                             Monongahela River Basin    Not substantial.
                             Population of the
                             Longnose Sucker as
                             Endangered.
03/29/2007................  90-Day Finding on a        Notice of 90-day      72 FR 14750-14759
                             Petition To List the       petition finding,
                             Siskiyou Mountains         Substantial.
                             Salamander and Scott Bar
                             Salamander as Threatened
                             or Endangered.
04/24/2007................  Revised 12-Month Finding   Notice of 12-month    72 FR 20305-20314
                             for Upper Missouri River   petition finding,
                             Distinct Population        Not warranted.
                             Segment of Fluvial
                             Arctic Grayling.
05/02/2007................  12-Month Finding on a      Notice of 12-month    72 FR 24253-24263
                             Petition To List the       petition finding,
                             Sand Mountain Blue         Not warranted.
                             Butterfly (Euphilotes
                             pallescens ssp.
                             arenamontana) as
                             Threatened or Endangered
                             with Critical Habitat.
05/22/2007................  Status of the Rio Grande   Notice of Review....  72 FR 28864-28665
                             Cutthroat Trout.
05/30/2007................  90-Day Finding on a        Notice of 90-day      72 FR 29933-29941
                             Petition To List the Mt.   petition finding,
                             Charleston Blue            Substantial.
                             Butterfly as Threatened
                             or Endangered.
06/05/2007................  12-Month Finding on a      Notice of Review....  72 FR 31048-31049
                             Petition To List the
                             Wolverine as Threatened
                             or Endangered.
06/06/2007................  90-Day Finding on a        Notice of 90-day      72 FR 31256-31264
                             Petition To List the       petition finding,
                             Yellow-Billed Loon as      Substantial.
                             Threatened or Endangered.
06/13/2007................  12-Month Finding for a     Notice of 12-month    72 FR 32589-32605
                             Petition To List the       petition finding,
                             Colorado River Cutthroat   Not warranted.
                             Trout as Threatened or
                             Endangered.
06/25/2007................  12-Month Finding on a      Notice of amended 12- 72 FR 34657-34661
                             Petition To List the       month petition
                             Sierra Nevada Distinct     finding, Warranted
                             Population Segment of      but precluded.
                             the Mountain Yellow-
                             Legged Frog (Rana
                             muscosa).
07/05/2007................  12-Month Finding on a      Notice of 12-month    72 FR 36635-36646
                             Petition To List the       petition finding,
                             Casey's June Beetle        Warranted but
                             (Dinacoma caseyi) as       precluded.
                             Endangered With Critical
                             Habitat.
08/15/2007................  90-Day Finding on a        Notice of 90-day      72 FR 45717-45722
                             Petition To List the       petition finding,
                             Yellowstone National       Not substantial.
                             Park Bison Herd as
                             Endangered.
08/16/2007................  90-Day Finding on a        Notice of 90-day      72 FR 46023-46030
                             Petition To List           petition finding,
                             Astragalus anserinus       Substantial.
                             (Goose Creek milk-vetch)
                             as Threatened or
                             Endangered.
8/28/2007.................  12-Month Finding on a      Notice of Review....  72 FR 49245-49246
                             Petition To List the
                             Gunnison's Prairie Dog
                             as Threatened or
                             Endangered.
9/11/2007.................  90-Day Finding on a        Notice of 90-day      72 FR 51766-51770
                             Petition To List Kenk's    petition finding,
                             Amphipod, Virginia Well    Not substantial.
                             Amphipod, and the
                             Copepod Acanthocyclops
                             columbiensis as
                             Endangered.
9/18/2007.................  12-month Finding on a      Notice of 12-month    72 FR 53211-53222
                             Petition To List           petition finding
                             Sclerocactus brevispinus   for uplisting,
                             (Pariette cactus) as an    Warranted but
                             Endangered or Threatened   precluded.
                             Species; Taxonomic
                             Change From Sclerocactus
                             glaucus to Sclerocactus
                             brevispinus, S. glaucus,
                             and S. wetlandicus.
----------------------------------------------------------------------------------------------------------------

    In FY 2007, we provided funds to work on proposed listing 
determinations for the following high-priority species: 3 southeastern 
aquatic species (Georgia pigtoe, interrupted rocksnail, and rough 
hornsnail), 2 Oahu plants (Doryopteris takeuchii, Melicope hiiakae), 31 
Kauai species (Kauai creeper, Drosophila attigua, Astelia waialealae, 
Canavalia napaliensis, Chamaesyce eleanoriae, Chamaesyce remyi var. 
kauaiensis, Chamaesyce remyi var. remyi, Charpentiera densiflora, 
Cyanea eleeleensis, Cyanea kuhihewa, Cyrtandra oenobarba, Dubautia 
imbricata ssp. imbricata, Dubautia plantaginea ssp. magnifolia, 
Dubautia waialealae, Geranium kauaiense, Keysseria erici, Keysseria 
helenae, Labordia helleri, Labordia pumila, Lysimachia daphnoides, 
Melicope degeneri, Melicope paniculata, Melicope puberula, Myrsine 
mezii, Pittosporum napaliense, Platydesma rostrata, Pritchardia hardyi, 
Psychotria grandiflora, Psychotria hobdyi, Schiedea attenuata, 
Stenogyne kealiae), 4 Hawaiian damselflies (Megalagrion nesiotes, 
Megalagrion leptodemas, Megalagrion oceanicum, Megalagrion

[[Page 6683]]

pacificum), and one Hawaiian plant (Phyllostegia hispida (no common 
name)). In FY 2008, we are continuing to work on these listing 
proposals (we are now including an additional 17 species in the Kauai 
species proposed listing determination package). In addition, we are 
continuing to work on several other determinations listed below, which 
we funded in FY 2007 and are scheduled to complete in FY 2008.

         Actions Funded in FY 2007 That Have Yet To Be Completed
------------------------------------------------------------------------
                  Species                              Action
------------------------------------------------------------------------
           Actions Subject to Court Order/Settlement Agreement
------------------------------------------------------------------------
Wolverine.................................  12-month petition finding
                                             (remand).
Western sage grouse.......................  90-day petition finding
                                             (remand).
Rio Grande cutthroat trout................  Candidate assessment
                                             (remand).
------------------------------------------------------------------------
                    Actions with Statutory Deadlines
------------------------------------------------------------------------
Polar bear................................  Final listing determination.
Ozark chinquapin..........................  90-day petition finding.
Tucson shovel-nosed snake.................  90-day petition finding.
Gopher tortoise--Florida population.......  90-day petition finding.
Sacramento valley tiger beetle............  90-day petition finding.
Eagle lake trout..........................  90-day petition finding.
Smooth billed ani.........................  90-day petition finding.
Mojave ground squirrel....................  90-day petition finding.
Gopher Tortoise--eastern population.......  90-day petition finding.
Bay Springs salamander....................  90-day petition finding.
Tehachapi slender salamander..............  90-day petition finding.
Coaster brook trout.......................  90-day petition finding.
Mojave fringe-toed lizard.................  90-day petition finding.
Evening primrose..........................  90-day petition finding.
Palm Springs pocket mouse.................  90-day petition finding.
Northern leopard frog.....................  90-day petition finding.
Shrike, Island loggerhead.................  90-day petition finding.
Cactus ferruginous pygmy owl..............  90-day petition finding.
------------------------------------------------------------------------

    Our expeditious progress so far in FY 2008 in the Listing Program, 
includes preparing and publishing the following:

                                        FY 2008 Completed Listing Actions
----------------------------------------------------------------------------------------------------------------
     Publication date                 Title                   Actions                      FR Pages
----------------------------------------------------------------------------------------------------------------
10/09/2007................  90-Day Finding on a        Notice of 90-day      72 FR 57278-57283
                             Petition to List the       Petition Finding,
                             Black-Footed Albatross     Substantial.
                             (Phoebastria nigripes)
                             as Threatened or
                             Endangered.
10/09/2007................  90-Day Finding on a        Notice of 90-day      72 FR 57273-57276
                             Petition To List the       Petition Finding,
                             Giant Palouse Earthworm    Not substantial.
                             as Threatened or
                             Endangered.
10/23/2007................  90-Day Finding on a        Notice of 90-day      72 FR 59983-59989
                             Petition To List the       Petition Finding,
                             Mountain Whitefish         Not substantial.
                             (Prosopium williamsoni)
                             in the Big Lost River,
                             ID, as Threatened or
                             Endangered.
10/23/2007................  90-Day Finding on a        Notice of 90-day      72 FR 59979-59983
                             Petition To List the       Petition Finding,
                             Summer-Run Kokanee         Not substantial.
                             Population in Issaquah
                             Creek, WA, as Threatened
                             or Endangered.
11/08/2007................  Response to Court on       Response to Court...  72 FR 63123-63140
                             Significant Portion of
                             the Range, and
                             Evaluation of Distinct
                             Population Segments, for
                             the Queen Charlotte
                             Goshawk.
12/13/07..................  12-Month Finding on a      Notice of 12-month    72 FR 71039-71054
                             Petition To List the       Petition Finding,
                             Jollyville Plateau         Warranted but
                             salamander (Eurycea        Precluded.
                             tonkawae) as Endangered
                             With Critical Habitat.
1/08/08...................  90-Day Finding on a        Notice of 90-day      73 FR 1312-1313
                             Petition To List the       Petition Finding,
                             Pygmy Rabbit               Substantial.
                             (Brachylagus idahoensis)
                             as Threatened or
                             Endangered.
1/24/2008.................  12-Month Finding on a      Notice of 12-month    73 FR 4379-4418
                             Petition To List the       Petition Finding,
                             Siskiyou Mountains         Not Warranted.
                             Salamander (Plethodon
                             stormi) and Scott Bar
                             Salamander (Plethodon
                             asupak) as Threatened or
                             Endangered.
----------------------------------------------------------------------------------------------------------------

    Our expeditious progress also includes work on listing actions, 
which we are funding in FY 2008. These actions are listed below. We are 
conducting work on those actions in the top section of the table under 
a deadline set by a court. Actions in the middle section of the table 
are being conducted to meet statutory timelines, that is, timelines 
required under the Act. Actions in the bottom section of the table are 
high priority listing actions, which include at least one or more 
species with an LPN of 2, available staff resources, and when 
appropriate,

[[Page 6684]]

species with a lower priority if they overlap geographically or have 
the same threats as the species with the high priority.

     Actions Anticipated To Be Funded in FY 2008 That Have Yet to be
                                Completed
------------------------------------------------------------------------
                  Species                              Action
------------------------------------------------------------------------
           Actions Subject to Court Order/Settlement Agreement
------------------------------------------------------------------------
Bonneville cutthroat trout................  12-month petition finding
                                             (remand).
------------------------------------------------------------------------
                    Actions With Statutory Deadlines
------------------------------------------------------------------------
Polar bear................................  Final listing determination.
3 Southeastern aquatic species............  Final listing.
Phyllostegia hispida......................  Final listing.
Yellow-billed loon........................  12-month petition finding.
Black-footed albatross....................  12-month petition finding.
Mount Charleston blue butterfly...........  12-month petition finding.
Goose Creek milk-vetch....................  12-month petition finding.
White-tailed prairie dog..................  12-month petition finding.
Mono Basin sage grouse (vol. remand)......  90-day petition finding.
Ashy storm petrel.........................  90-day petition finding.
Longfin smelt--San Fran. Bay population...  90-day petition finding.
Black-tailed prairie dog..................  90-day petition finding.
Lynx (include New Mexico in listing)......  90-day petition finding.
Wyoming pocket gopher.....................  90-day petition finding.
Llanero coqui.............................  90-day petition finding.
Least chub................................  90-day petition finding.
American pika.............................  90-day petition finding.
Dusky tree vole...........................  90-day petition finding.
Sacramento Mts. checkerspot butterfly.....  90-day petition finding.
Kokanee--Lake Sammamish population........  90-day petition finding.
206 species...............................  90-day petition finding.
475 Southwestern species..................  90-day petition finding.
------------------------------------------------------------------------
                      High Priority Listing Actions
------------------------------------------------------------------------
31 Kauai species \1\......................   Proposed listing.
8 packages of high-priority candidate       Proposed listing.
 species.
------------------------------------------------------------------------
\1\ Funds used for this listing action were also provided in FY 2007.

    We have endeavored to make our listing actions as efficient and 
timely as possible, given the requirements of the relevant law and 
regulations, and constraints relating to workload and personnel. We are 
continually considering ways to streamline processes or achieve 
economies of scale, such as by batching related actions together. Given 
our limited budget for implementing section 4 of the Act, these actions 
described above collectively constitute expeditious progress.

Conclusion

    We will add the montane portion of the Gunnison's prairie dog to 
the list of candidate species. We intend any listing action for the 
species to be as accurate as possible by reflecting the best available 
information. Therefore, we will continue to accept additional 
information and comments on the status of and threats to this species 
from all concerned governmental agencies, the scientific community, 
industry, or any other interested party concerning this finding. If an 
emergency situation develops that warrants an emergency listing of this 
species, we will act immediately to provide additional protection.

References

    A complete list of all references cited herein is available upon 
request from the Western Colorado Field Office (see ADDRESSES).

Author

    The primary authors of this document are staff located at the 
Colorado Field Office (see ADDRESSES).

Authority

    The authority for this action is the Endangered Species Act of 
1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: January 29, 2008.
H. Dale Hall,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 08-493 Filed 2-4-08; 8:45 am]
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